I avoid moderation at all costs (I don't moderate any content on any of
the social networks I manage, my facebook page, blog comments...none of
it).
The main reason you'd moderate is to stop people saying crazy things or posting inappropriate content.
The problem with moderating is that it makes your readers feel like you don't trust them...don't you love the way they compare your receipt to what's in your cart at Sam's Club as if you're trying to steal from them. Moderation also robs your users of the instant gratification of seeing their content on your site.
I'd prefer to have the occasional comment that I have to delete after the fact than to create a full time job of moderating comments.
If something does slip through the cracks, folks understand that it wasn't you who posted it...and I promise, someone will let you know about it really quickly.
I've got thousands of people on social networks that I oversee and I receive about one content complaint a month. It's not worth telling your readers you don't trust them to prevent the one idiot who's going to abuse the system.
I can't wait to see the comments this post gets!
Update: A reader sent me this post from Guy Kawasaki: The Top Ten Stupid Ways to Hinder Market Adoption (check out #11)