KavaTunes will let you build a website that looks and works just like iTunes. You can have all of your music and playlists anywhere you have an internet connection.
It’s also a fun way to just show what is in your library. You can set a preference to have your iTunes collection on the site, but not have any songs playable. So, if you’re a DJ and want to show potential clients what you have to offer, you can send them to the site.
Kavatunes is $35 and can be found on the KavaTunes site.
If you’re going for more of a media server, Remote Buddy will be a great tool for you.
It has been around for a while allowing you to control nearly everything on your Mac with a bluetooth remote. Just recently, it also provides a really nice AJAX interface for you to use with your iPhone. Once the server is started up, you can load the interface into your iPhone browser.
Front Row now allows an interface for a lot of these features, but if you’d like to work with more than media this application comes in handy. Also, older Macs without the infrared remote can work via bluetooth.
A demo of the application can be found at the IOSpirit homepage.