Do you think that it's necessary for a forum to require a user to click a link sent to them via email upon registration? Personally I think it totally gets in the way and is obnoxious. There were quite a few forums that I wanted to post on, realized I had to register, registered, then just didn't feel like opening up Outlook and ended up leaving the site forever. Is that just me?
What I've done at this site is made it so that you have to verify your email. But, upon registering, you still have the ability to post and create threads. You then need to verify your email to be able to have access to the User Control Panel, avatars, signatures, member profiles, private messages, etc. This way we don't lose prospective members who want a simple, quick way to join in on a thread.