I'm an enthusiast for answering questions - I like to be able to contribute to the 'wisdom of the internet' in a positive way. I've answered a few questions on ServerFault, but not as many as I'd have liked.
Aside from poor initial questions, the other reason I trip up is because some questions are extremely specific. That's an artifact of the target audience - we want people to have done their own initial research. However it also means that if I haven't encountered the specific problem listed, I often can't offer much, as I may not be able to reproduce the problem.
Regarding the first point though - there's a bit of a firehose of questions coming in, and most are outside my specialist subject area. It would be useful to be able to customise and filter my 'new questions' view. I'm a storage engineer by trade - I know my way around RAID, disks, volume managers, arrays etc. I'm never likely to have anything useful to say about apache. (Well, basic questions that probably shouldn't be here in the first place; maybe).
I would also perhaps suggest an 'approval' mechanism for submitting questions (maybe reputation geared?). So we can have an 'anonymous' question queue, and a 'established user' question queue? (With the caveat that we'd expect established users to 'approve' suitable 'anonymous' questions).
This is an approach that works fairly well on PerlMonks - the 'approved' marker is one you can filter on, or not, as you wish. Established community participants can 'approve' a new post, and do so based on ... well, it's up to them.
Edit: Also, I don't know if it's been suggested before - but would setting financial bounties as well as rep also be an incentive? On one hand, it's compensating for effort, but it might server to discourage the enthusiasts/volunteers who contribute in the first place.