"Some of the domains wanted threads have been there forever.
Newbies come in and post to those threads wiht no replys.
Can you delete some?"
I agree. And unless the potential purchaser comes back in and posts that he/she is no longer "wanting", how are we to know ... and thus, stop posting domains? I know this has come up before.
Simply wanted to post and put in my vote for a purge, as well. I'm sure Greg and the folks will eventually do what is best!

Good Luck.