I like the site slickdeals.net. It's kind of heavy on the electronics, but it does have some pretty great tips with some regularity. For example, I just found a tip for cashback from microsoft on puchases made after doing a search on live.com. The results page looks something like this:
The results that have the little gold coin give you varying chances for cashback (30% for ebay and 7% for live.com in this shot). You go there and have 60 minutes to buy something with paypal to get the rebate. Anything in that session gets the discount according to the terms. It just saved me $90. At least, in theory. I still have to wait the obligatory period before I can cash in, but it seems like a great chance to save money.