I've been using Stumble Upon for a while now. Stumble Upon is a browser add in that lets a user randomly find web pages that match certain interests. I normally use this when I'm pretty bored and can't think of anything else to do. Normally, I find a few humorous quotes or a Flash presentation, but nothing that takes a lot of time.
Tonight however, about the time I needed to go bed, I ran across a Flash game called Grow RPG by eyemaze.com. This is actually a puzzle where you have to place 8 pieces in a particular order. After each piece is laid, some of the previous pieces “GROW” based on the order in which you placed them. Once all the pieces are laid, your character attempts to fight a few creatures. You know how well you did based on far he gets before he dies.
It sounds simple, but if my math is correct, there are 40320 ways the eight pieces can be placed. It took me over an hour to solve it. I fumbled around for a bit, got frustrated, looked online for the solution, couldn't find that fast enough to suit me but did find some kid who solved in in 10 minutes. After my pride recovered, I sat down with a pen a paper and spent the next hour working it out (it would be much faster if you didn't have to watch the animations each time). It was fun but it should have started earlier than 10:30 PM.