I've been a geek since forever, so when I just found this my whole childhood flashed before my eyes. It's the Internet Archive's new collection of vintage software from "back in the day" and it's all useable right in your browser. O.M.F.G.
Yes, there are lots of games, but classic "real" software like WordStar and Visicalc too.
I may never get any work done ever again.
Update: Welcome C&L readers. Please enjoy yourselves and have a look around: beer's in the fridge, we have some nice Oregon Pinot Noir in the cellar and a few bottles of single malt in the cupboard. Help yourselves.