This post is from GRS staff writer Donna Freedman. Donna writes a personal finance column for MSN Money, and writes about frugality and intentional living at Surviving And Thriving. Since she just found out she is going to be a grandmother, expect to be bombarded with cute-baby anecdotes about seven months from now.

If you draw a paycheck, you’re due an extra $160 in January and February thanks to the Temporary Payroll Tax Cut Continuation Act of 2011.

What’re you gonna do with your windfall? Maybe not much. It’s pretty easy to miss $20 more in salary, especially if fixed expenses (groceries, insurance, child care, gasoline) keep going up.

Note: This is not a political column. I repeat: This is not a political column. I really don’t care what you think about the payroll tax cut. Please keep all your “#$@!# dumb-o-crat policies” or “#$@!# con-man-servative hatefulness” comments until a later date. Like, um, never. Get Rich Slowly is a personal finance site, not a flame-throwing political forum. Thank you for not foaming.

Technically you have two choices: Save it or spend it. I’d like to suggest a third: Save it or spend it intentionally.

You could go out to lunch a couple of times each week. You could treat yourself to $20 worth of cupcakes or ceramic clowns from the dollar store. Or you could convince yourself that each double sawbuck represents an opportunity to improve your life.

Which it does — if you look at it the right way.

If someone offered you $160 in cash, you’d probably grab it. (And if you didn’t, can I have yours?) But to some people, an “extra” $20 a week seems penny-ante.

Thanks to rampant ATM use, $20 bills have become the coin of the realm. I believe this has devalued them in the popular imagining — and there’s no denying that $20 doesn’t go very far these days.

True and cumulative costs
In particular, it doesn’t go very far if we fail to pay attention to spending. We grab a soda and some chips when we go in to pay for gas. We add a magazine and a few packs of gum at the grocery checkout counter. We always get popcorn at the movies because, well, we just do, that’s all.

It’s only $3, or $5, or $7. Besides, we deserve it.

That’s how some people get into trouble in the first place: By neglecting to frame expenses in terms of their true and cumulative costs. Dropping a few hundred dollars on a spur-of-the-moment weekend getaway is great fun at the time, but you may regret it if you can’t pay the balance in full.

The money you spent (and continue to spend, in the form of credit card interest) also is cash that can no longer be used in a smarter way, such as retirement or a pay-cash-for-a-car fund.

Let me be clear: I am not saying that you can never have any of the things you want. In fact, I am learning — slowly! — to spend a little money on myself. So if you’re in a position to drop that extra $20 per week on chai tea or sheet music, by all means drop it.

And if not? Make those temporary twenties work damned hard for you — and incidentally, their job might be to pay for something fun, such as frugal entertainment.

Pay it down, or pay it forward
How can you put that money to work? Use it for the following:

  • Emergency fund. Not to belabor the obvious, but that $160 is a nice fund-plumper. And if you’re brand new at this, the sum is nearly one-third of the $500 that Liz Weston says you need in the bank.
  • Retirement. Put the money into your Roth IRA or whatever other fund you have. (Don’t have one? Let this be the seed money.)
  • College fund. Add an extra $160 to Junior’s post-secondary plan.
  • Pay down debt. One hundred and sixty dollars = a nice debt snowflake.

Shopping, if you must:

  • Nonperishables. Flour, sugar, dry beans, tuna, rice, canned goods, pasta, your favorite cereals — and give yourself bonus points for buying on sale with coupons. Your grocery bill will drop a bit for the next month or two as you eat your way through the storehouse. And if something unexpected happens (illness, car repairs, job loss), you’ll congratulate yourself on having a well-stocked pantry.
  • Pet supplies. When you see a screamin’ deal on food or litter at PetSmart or PETCO, stock up. Improve the sale price by paying with plastic scrip from a discounted gift card site.
  • Cut-rate couture. Watch for end-of-season sales on wardrobe basics you know to be durable and comfortable. You might not have to buy work slacks for a year or two. Or browse a thrift store or consignment shop — again, looking for clothing that’s well-made and flattering. What fun to see how far a $20 bill will go, especially on 50-Cent Day. (I’m referring to the price tag, not the rap star.)
  • Shoes. Use price-comparison and cash-back sites as noted above to find sale prices on your favorite make and model. I recently ordered three pairs of my favorite old-lady comforts for about $153 (minus the nearly $11 cash-back rebate).
  • Socks and undies. Bor-ing? You betcha. But elastic isn’t forever and your socks will eventually develop holes. When crew socks and tighty-whities go on sale, buy half a dozen or more of each.

For the health of it:

  • New glasses/contacts. Still squinting through those three-year-old specs? Discount eyewear emporia regularly offer coupons in newspapers and Valpak envelopes, and through online coupon sites like Savings.com and Retail Me Not. Oh, and stock up on contact lens solution when it goes on sale.
  • Vitamins. Aim for a three- or six-month stash of your favorite supplements. Use a price comparison website like Price Grabber or Cheap Uncle to find the best deals, and see if the lowest-priced merchant can be accessed through a cash-back shopping site like Mr. Rebates, Extrabux or FatWallet.
  • OTC meds. Restock your medicine cabinet with analgesics, bandages, antibacterial ointments, allergy meds and the like. You may be able to get these free or nearly so by combing coupons and rebates.
  • Dental work. Don’t have dental insurance? Me neither. But I regularly see social commerce vouchers and Valpak coupons for X-rays and cleanings. They cost $30 or less. A professional cleaning and a big-picture look at incipient problems may even save your life.

That’s entertainment:

  • Discounted movie tickets. Warehouse clubs sell them. However, you might get a much better deal through — yep — a discounted gift card site.
  • Annual pass. Museums, zoos, botanical gardens, opera, the orchestra — whatever floats your boat.
  • The Entertainment Book. It’s full of BOGOs for city attractions from art to boat tours. Buy it through a cash-back site for a rebate of up to 35% plus free shipping.
  • Condoms. Go ahead and snicker. But not having protection can be pretty damned expensive in the long run. I know a couple whose second child is on planet Earth because “we were out of birth control and decided to take a chance.” No, I couldn’t believe it, either.

Thinking ahead:

  • Warehouse club membership. Even studio dwellers might be able to buy in bulk if they’re creative about storage.
  • Go green. Replace some incandescent bulbs with LED or compact fluorescent bulbs and trim your electric bill. Faucet aerators and low-flow showerheads reduce both energy and water/sewer bills. If the commode in your abode is really old, consider a water-saving toilet.
  • Car care. Watch for sales on fluids (antifreeze, windshield washer, a case of motor oil, et al.), filters and replacement wiper blades. If your tires have receding treadlines watch for sales on those, too. (Don’t forget Craigslist. A friend bought four high-quality, nearly new tires for $100.)

Ant or grasshopper?
The grasshopper generally has a swell summer: long days at the beach, trips to amusement parks, ice cream for breakfast. Meanwhile, the ant is weeding the garden, clipping coupons and hanging all his laundry to dry outside.

Once the temperature drops, the grasshopper is likely to regret his profligacy. The ant, meanwhile, has a storeroom full of pinto beans and tube socks. All the windows have been caulked, too.

Of course, it’s your money and therefore your decision. But try thinking of your $160 in ways like these:

  • One night at a nice hotel, or an extra chunk of fundage into your Roth. (Oh, compound interest, I’ve missed you so! Let’s never fight again!)
  • A couple of months’ worth of cable vs. new glasses. (What good is TV anyway if you can’t see it?)
  • Dinner for two at a nice restaurant, or some depth to your pantry.

One more suggestion: Split the difference. Get yourself $80 worth of truffles and apps and $80 worth of something less than sexy but ultimately beneficial, such as cat litter or dental X-rays. Even $40 will pay for a fair amount of decadence, especially if you use a coupon.

This article is about Frugality, Savings