Okay, sorry for being vague. I do that a lot, expect people to know. It's the manager in me, lol.
On the top nav bar, along with User CP, New Posts, etc, etc there's a link "Top 5". Or "Top Games" or "Top Cars", whatever your forum deals with. For this, I'll use movies.
Each user in their User CP has a Top Picks page or box or option. There are 5 drop down boxes with a certain number of movie titles. Each box has a ranking, 1 thru 5. 1 being the highest, 5 lowest. The user can rank their favorite movies, or what they're currently watching on DVD, or whatever the case may be.
The top ranked movie in the user's list would recieve 5 points, the lowest would recieve 1 point. You can view each individual user's top 5. But, also those points are added to a database for the entire site. So, adding up the movies, a overall Top5.php could be generated ranking the most popular movies.
Included on the Top5.php, aside from the most popular movies, you could see the active movement. If The Passion of the Christ was number 1 last week, but is number 3 this week, you can see "Previous position" next to it's current position. Or "NEW" if the movie wasn't on there last week. Maybe not weeks, but updated as specified by the admin.
For my site, I'd be using this to see what games people are currently playing on Xbox Live. If a hot new game is released, you could see that people are playing Splinter Cell: Pandora tomorrow the most, but Rainbow Six 3 is still right up there.
It'd work with movies, music, fantasy sports, etc. It's like the weekly movie/sales charts, only the users determine what's hot
I hope that helps. Ask any other questions if you want.