Most of us have heard of spackling paste used to fill in nail holes. The tub will cost you $10 or so and you will also need a small putty knife to scrape off the left over spackle.
Now if you're not doing a full on board and batten project and don't need filler for larger holes, then you're in luck. A much easier and way more affordable solution is soap. Just grab a bar of soap, rub it across the hole, wipe away any left over soap around the hole with paper towel and VOILA!
Thanks a bunch to Ms. Budget Savy Diva at www.BudgetSavyDiva.com for the creative idea!