A custom-written content management system that I wrote using PHP and MySQL hosted on a Linux server. Hurray [free] open source!
Though I'd be fine with any *nix-based OS for the server, such as any Linux distro or Max OS X. 
Edit: Though if you want REALLY simple coding, check out
Ruby on Rails. You can even
learn it using an nifty online terminal. Using Ruby on Rails, ,there have been people who have coded an entire online forum in
less than 500 lines of code. Personally, Ruby on Rails has been on my "if I had some free time I'd love to learn this" list for a while.