Bluefish Editor - a powerful editor targeted towards programmers and webdesigners.
I decided to work and give my contribution to the editor I use and depend on coding in Ubuntu Linux. Auto complete is huge when coding and it's one of the contributions I decided to work on. So far, I'm building up a CSS3 Auto complete library and APACHE Snippets for free that will be available for Bluefish when done. Other ideas I've given have already been built-in by the awesome developers.
Here's some screenshots of the auto complete in development on the current version of Bluefish:
