I looked around and didn't see much of a thread for this, so I figured it'd be a good thing to start one. I like buying things for cheap, and I'm sure some of you all too. If you see a good deal, post it on here. Include a date when you found it, so we know how likely it is to last.
I'm putting down the gold box deals of the day at Amazon for 3/22/10. Basically, there's one item that's discounted all day, and 4 other things ("lightning deals") that are discounted for about 3 hours at a time. The games aren't revealed until the discount applies, but Amazon does give some broad hints (and some really specific ones to).
Dante's Inferno for $40 (PS3 and 360, all day)
Tekken 6 for $20 (PS3, expires at 1 PM Pacific)
RPG discount from 1-4 PM Pacific (maybe ME2 for PC?)
Lego Indy from 4-6 PM Pacific (not sure which platforms)
PS3 Game from 6-8 PM Pacific (Hint is "Wave around your PS3", some kind of eyetoy game?)
MMA Tapout from 8-10PM Pacific (not sure which platform)
If you want instantaneous updates, look up AmazonDeals on twitter.