I follow ToDoOrElse.com by Bob Walsh (author of Micro-ISV: From Vision to Reality), where he writes interesting things on GTD. But I have to admit that at least as far as coding is involved, there is only one rule that works for me:

Open the editor and force myself to start coding.

Sometimes I write bad code this way which I later have to rewrite, but at least I don’t start the endless loop of checking email, reading forums / blogs, surfing etc. Unfortunately this brute force approach doesn’t work with other tasks.