For the forums. Maybe the code could pick a user at random and display a 'Member of the Week' title in his/her profile? Then their profile could be displayed in a block on the front page or something.

Also, I was thinking it would be good to have a MOTM archive that displays past members just in case someone wants to look them up.

Just an idea I had.

Not randomly picked.. instead.. an user with higest point (based on his contributions/forum post..)

Not much useful but interesting (fun) feature ;-)..

PS: I am sure, most sites will show only site admin's name as user's of month .. he he.

Yes, it would be purely for fun, it's just something that could improve the forums and encourage people to join a site.

Good idea. Count user post for last 7 days maybe? Ignore count for admins and mods?

You should create a separate post count table and use date for every post. This means 50 posts = 50 rows x 10 users = 500rows... i suggest to you to reset that table every 7 days or it could became very very big and slow