Okay, I know everybody's having fun knifing bums and hiding in the park in GTAIV, but I'm stuck slogging it through my massive backlog of games (that may sound like complaining, but it's fun), all the way back to Wizardry 6... ahem!...
Anyway, after getting the chance to play GTAIV at a friend's house, I was tempted to bust out my old GTA games (I've got all the others for the consoles). I decided that I could allow myself to play games like GTA3 and not "cheat" in my black-slogging as long as I didn't do anything to advance the story, so I've been driving around, making "mini games" for myself - doing vigilante missions, sweet jumps, deciding to exterminate pimps, set fire to hobos, etc.
I wanted to see if anybody else had some old-school GTA diversions - any game but the current one is fair game. I've seen people go so far as to come up with "new missions" on other sites, which is a bit more work than I'm looking for, but if it's fun for you let us know (assuming there's an "us" here and it's not just me playing the old games).
My current "mini-game," post-pimp-killing, is to see how long I can drive on JUST the sidewalks for, and also to get a good head of steam on the firetruck before plowing into oncoming traffic to see how far they spiral off to... :P