I've taken various online ones, several which seemed very trustworthy...I really don't trust the answers that much anyway. I got 130-150 the times I took it.
LEFT4DEAD411.COM
Bet with disolitude: Left4Dead will have a higher Metacritic rating than Project Origin, 3 months after the second game's release. (hasn't been 3 months but it looks like I won :-p )