[Analogpoint]

What I would love to see is a captcha after you don't get your password right once or twice, that would prevent bots from trying to brute-force a users password and get their account locked out after 5 tries. The benefit is that my users won't get pissed about having to type in a captcha every time they log in.

As far as preventing spam postings, you can restrict URLs and Images from users with fewer than 5 posts or so, that would take care of most spam, and then you can try the akismet plugin to catch the rest of the spam. Works like a charm for me.