I've completed what seem to be the least frustrating of all the Crackdown achievements (but Repo Man was such a HUUUUUGE bitch. It sucked big time, 'cause the game is really picky about what counts as "commandeering a vehicle.")

Now, onto the big ones (aside from the co-op ones, which can be easily done, I just don't have anyone to co-op with). Finding all the stunt markers, then actually driving through them is gonna be tough... then there's finding the 20-something agility orbs I'm missing. Sure, 20 might not seem like a lot, and it really isn't, but the fact that there are 500 orbs in all, and they're all strewn about the four islands...well, it's like finding needles in multiple haystacks. And then there are the 200-something hidden orbs I have to find, which are actually hidden within building and in caves and out in some obscure location of the coast and stuff like that. That's gonna be a bitch, too.