I would like to add my vote for strongly considering code completion in TM. It's the one area that I've had to work around in replacing my old web development tools. I abhor wizards and the like, but when I'm in the middle of typing 'text' in a stylesheet, it's really nice to have it offer me '-indent' and '-decoration', etc. Upon selecting an option (pressing enter) I'm used to it determining the context and building the necessary structure, in this case the colon and semicolon. CSSEdit does a pretty decent job with this type of completion, within the realm of a CSS file, of course.
Personally, I agree with the earlier sentiment that if a solid code completion base were built, then those of us with language specific needs could begin tweaking and building the necessary libraries for each language. This would be a huge boon to TM, IMHO.
Brett