I spend much of my time on a forum called Overclockers UK, or OcUK for short (link) and from there I have built up a list of people I play on the Xbox 360 who I can be (fairly) sure are not cheaters, whingers or any of the other annoying types on Xbox Live. One annoying thing though is that not everyone uses their forum ID for their gamertag, so I loose track of who is who. So partly for my benefit, and partly because I think it'd help over on the forums, I've created a database of forum IDs and gamertags here.
Its powered by a PHP script that fetches the info from a table. Normally you can't call PHP code from a WordPress page but I found a plugin that will let you: runPHP. I was a bit concerned that if the plugin broke it would expose the PHP and perhaps let those nasty script kiddies into my database so all the PHP code does is include another separate script somewhere else on my website. PHP security is not my speciality, I'm sure I'll soon find out if I left any holes anywhere!