This seems to be a very cool tool I've just discovered. It runs in the tray and turns Query Analyzer (I'm not sure about other editors) into a full featured editor! It includes intellisense with auto-complete, snippets, formatting, etc.
It is currently free, but not for long. Once version 3 is released (sounds like sometime this month), they are going to start charging for it.
SQL Intellisense, Intellisense for SQL Server - SQL Prompt