As a broke college student and a girl raised by a woman who practically worshiped coupons and sales, I absolutely love legit sites that give me free samples/discounts/gift cards/etc. I usually use them to get stuff I want either really cheap or free. Getting $100 worth of stuff for completely free with accumulated gift cards = best 20th birthday ever, y'all.
Obviously, I just joined Eden's Points program. Free sex toys, here I come!
I do Swagbucks a lot too. I've redeemed about $125 in gift cards, mostly Amazon, so far. I buy the Paypals whenever they go on sale.
I also do MyPoints, which gives you points for every dollar you pay at an online store (Wal-Mart, Target, B&N, Restaurant.com, etc.) and each e-mail from them you "read." I've redeemed about $125 in Paypal and Amazon so far.
Hey, It's Free! is more of a newsletter, but I've gotten some really good freebies and promotions from reading it (free Amazon Prime membership, free Amazon mp3/video credits, full size samples, contests, etc.).
Recyclebank may take forever if you don't have a participating area, but I've gotten free magazine subscriptions from them. I collect most of my points when Hey, It's Free! gives word. My brother also uses My Coke Rewards to get free Entertainment Weekly subscriptions.
Oh, and there's also the usual survey sites. I get surveys the most often from e-Poll. The maximum award value is $30 bucks, but prizes include charity donations, Amazon, Paypal, Best Buy, and AMC theatre tickets.
I have more sites, but I feel these are the most significant/most often used for me.
Totally putting this thread on alert. Any other chances to get free/discounted crap is a great one for me!