The little things really do make a difference -- a $487.50 difference if you're willing to examine your spending under a microscope.

If you've been playing along side us during this month-long Fiscal Fitness '09 series, rest easy: You've already done most of the heavy lifting in weeks one and two where the regimen included the important steps of tracking your spending money and then slashing those big-ticket, infrequent bills.

This week was all about whittling down some of those under-the-spending-radar expenses. According to a Visa USA poll, one in five of survey respondents reported $25 of unaccounted spending a week, and 7% of those with holes in their wallets said they lose track of $100 or more a week.

You may be tempted to blow off the little stuff, and that's OK. As I've said before, the best use of your energy is to find ways to save on big-ticket expenses and then work your way down the list.

Still, the small stuff does add up, as we proved this week. Check out how ...

Monday: Stop "mystery spending" and save $200 a month.
That Visa survey mentioned above found that half of Americans lose track of more than $2,000 in cash a year -- $2,340, to be exact. This so-called "mystery spending" typically happens when we're having fun out on the town, shopping with kids, sucked into mall markdown madness and when the kids are in tow.

With those spending triggers in mind, we spent the rest of the week finding ways to remove the cloak of secrecy from that cash and put it to better use.

Tuesday: 3 ways to save $100 on groceries.
No coupon clipping required. Our supermarket shopping tips concentrated on ways to save even if you're stuck shopping while starving, and they don't all require you to go buy a membership at Costco (NASDAQ:COST) or BJ's Wholesale (NYSE:BJ). One trick is to simply avoid pre-chopped, pre-sorted, pre-packaged "convenience foods" that manufacturers like Kraft Foods (NYSE:KFT) make it so easy for you to buy. When Consumer Reports sent two shoppers to the supermarket for the weekly basics, the one schooled on the cost of convenience rang up a tab that was $79 less.

As Fool member KWT8011 pointed out, you shouldn't blindly rely on this rule-of-thumb: "I've noticed as of late it has been cheaper to buy pre sliced meats and cheeses than going to my deli. It is rare to find ham or turkey at a normal grocery store where I live under $6/lb. I also noticed preshredded cheese tends to run about as much as block."

In other words, do a quick price comparison before you toss anything in your cart. That per-unit pricing label on the shelf is a lifesaver.

Wednesday: Stop paying to heat the whole neighborhood.
Those small drafts in your home are sucking good money right out the window, and your old refrigerator isn't helping those electric bills. But with times as tight as they are, the new energy-efficient appliances you'd find at Sears (NASDAQ:SHLD) or Lowe's (NYSE:LOW) may be beyond your budget.

So we donned our overalls and found ways to plug the leaks and slash those utility bills by 30%. Based on the amount the average household spends on utilities per year -- $1,500 -- that's $12.50 to $37.50 a month just to weatherproof a few windows and regulate the temperature when you're not at home.

Thursday: Remove the "guilt" from your "guilty pleasures."
When it comes to personal finance advice, it always seems to be us versus Starbucks (NASDAQ:SBUX). But when we asked you to share those things you buy but maybe shouldn't, you didn't hold back. Thanks for sharing, since we think it's perfectly fine to spend your money on things that bring you joy, so long as you can afford them (and they aren't a fire hazard).

Even better, we suggest making your "guilty pleasures" a part of your formal spending plan. Next time you're buying shoes at Nordstrom (NYSE:JWN), figure out how much you actually spend on these things that give you joy, and then cut back that amount in some other area of the budget. That way you can continue to enjoy your vices without the guilt.

Friday: Get cash for your cast-offs
We ended the week by rummaging around in the attic, garage, and that overstuffed junk drawer and magically turning our trash into cash. With our rundown of services devoted to selling unwanted stuff, we managed to clear a cool $150. That's a lot more than can be made by rummaging through the couch cushions.

All told, this week's tips racked up $487.50 in spare change, proving that sweating the small stuff can pay off big. Add that amount to our running savings total, and we're already $272.07 over our $2,000 -- and we have one more week of tips to go!

Please chime in on the Fiscal Fitness '09 discussion board and let us know how much you've managed to save so far.

Read the latest from Fiscal Fitness '09: 1 Month, 2 Grand, 3 Stocks to get our other money-saving tips. You can also keep up with our tips through our daily Foolwatch email.

Fiscal Fitness boot camp instructor Dayana Yochim owns none of the companies mentioned in this article. Kraft Foods is a Motley Fool Income Investor pick. Sears Holdings, Starbucks, and Costco are Motley Fool Inside Value picks. Starbucks and Costco are Motley Fool Stock Advisor selections. The Fool owns shares of Starbucks. Try any of our Foolish newsletters today, free for 30 days. The Fool has a disclosure policy.