Oh, RoboRally. I don't know how many times my bot was destroyed on the first move thanks to another bot. And my friends won't play Risk with me anymore because I'm notorious for pitting everyone against each other.
For Tabletop RPGs, I've played DnD 3.0, 3.5 and 4e. I played Deadlands, which was a lot of fun, but did require someone who knew what was going on (especially during character creation). Used to play OWoD and Exalted, but the guy running those didn't know how to use a mat, and that killed most of the games when combat happened. I really enjoyed Savage Worlds due to its simplicity, but sadly most people would rather play DnD than that. Also played at least one game of Champions and d20 modern.
Also Monopoly is not fun, no matter what you think. Each game takes way too long, and it usually ends when one person suckers another into giving them a game breaking piece of property and then its the slow, agonizing defeat for the rest of the players.