W9 form requested by Forum vendor, what to do?

[the stig]

Tax season is here. I'm bumping my old thread for any (new) forum owner who is asked to provide their vendor with a W-9.

I have a quick question,
Are any of you forum owners created LLC? Can someone guide me how to do it (or who they have used to get it done?) Also, any benefit for LLC vs. being an individual?

**small background**
Launched an automotive forum back in 2008 "for fun" or thought I'd have a small group of friends browsing the forum. Forum blows up times 1000! Almost 40,000 members and millions of posts/threads later, I am debating if I should do a LLC."

thanks guys