The front page, where you can see the most recently updated backlogs
The main page of my personal backlog
As you can see, the Backloggery is a site where completionists can list all the games they've played or beaten over the years and show them off to friends. The site allows for showing the number of achievements in a game you've beaten, listing DLC, adding small reviews and notes and more. There's also a friend system where the right side of your main page is updated each time a friend updates their own backlog, and this is great for keeping up on what your friends are playing or how far along they are in a particular game.
So yeah, give it a try if you're as anal about keeping track of what you've done as I am, and feel free to add me while you're at it! My Backlog can be found here: http://www.backloggery.com/verranicus