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.