The CatsWhoCode.com blog has posted ten PHP code snippets that can help you connect with Twitter and perform certain actions like:
- Autofollow script
- Get Your Most Recent Twitter Status
- Twitter email grabber
- Timeline function
- RSS to Twitter
- Get the number of follower in full text
Those are the PHP examples from the list. There's a few more that are written in Ruby, Python and even a script that lets you update your status directly from vim.