Sometimes I have high priority question, and nothing draws attention to a question as +100 bounty. The thing is, I have to wait 2 days before I can set any bounty at all. Which might make sense for some SE sites with low traffic, but for example on SO, you can clearly see if the question is getting any attention after an hour or so.
Why can't setting bounty early be for example a privilege which you'd get with few thousand of reputation? After all if I'm a "trusted user", I should be trusted not to abuse the bounty system.
EDIT: it seems some of you assume, that asking question on SO is the first thing one would do, thus the 2 days to "do your homework" googling or whatever. In my case, and I guess in case of many ppl, I ask question on SO only after I couldn't get answer through usual channels like Google, Wiki, support forums etc. Thus actually this 2 day rule promotes "ask before you google" behavior, just to get the clock ticking.