I visit a lot of forums and something which is common on a few on them is a front page. This page gives loads of information, popular threads, guides and useful links, its also a place which will explain to the newbies what the website does, and at the bottom their can be a banner saying
'You need to be a paid seller to advertise here'
This may actually save a lot of mod time.
An example of the page:
http://www.buildyourown.org.uk/
Anyway, could help people quite a bit.
Matt