For syntax highlighting on the website, I'm using GeSHi. It is a very powerful tool written in PHP. It supports many computer languages, and I recommand it. Have a look on their website for examples and demos.

I've written a syntax file for F#. It might be included in a future version of GeSHi. You can use it freely (if you improve it, please tell me!). Here it is: http://laurent.le-brun.eu/pub/fsharp.txt