Craig's List
Craig's List (free online classifieds) has a free section for every city, so you can give away stuff, or pick up stuff that other's are giving away. We gave away our old fridge for free on Craig's List, and I got 3 emails about it within 10 minutes, and it was picked up that night.
I'm currently keeping an eye out for free bricks for a landscaping/curb appeal project for this summer, but there's all kinds of free stuff. The Denver Free stuff is here.
Free After Rebate
I've forgotten to send in the majority of rebate items I've purchased, but it's really worth it if you can take the time to address, stamp, and stuff an envelope. You fill out a form with your name and address, a copy of the receipt, and the UPC cut out from the item, and 8 weeks later you'll receive a check in the mail.
Freeafterrebate.info is the best site I've found for rebates. Everything on this site is $5 or less after rebate, and there's some nice stuff on there. Mostly tech stuff, but if you need some writable DVDs, a new keyboard, or a variety of other things, it's worth a look.
Thanks for the tip on the rebate site! I've been needing to get some rewritable CDs so I can stop stealing my brothers.
No problem! Also - all of these rebates can be done online, but a lot of them are for stores that we have locally, like Staples and Circuit City, so you can do 'in-store pickup' on the website, or just go into the store to get the deal.