[Adrian Schneider]

Don't advertise features, advertise content.

Features is really only useful to niche communities where the competitors do not have the same features as you and it's worth switching communities, or joining new communities for them. One of the few examples I can think of this is clan management for gaming sites.

However, even then, listing the number of clans (or groups) that you do have is much more interesting and valuable than whether or not you can do it.

Show stats for the common things (members, posts, active people, etc.) The biggest selling point to new members is how active the site is, and how relevant the information on it is to them.