The best place for info on vim (nowadays synonymous with vi), is at the vim website itself :
http://www.vim.org .
More specifically,
http://www.vim.org/scripts/index.php -- for scripts, plugins, file type plugins, custom syntax hilighting, and colorschemes. Most of what you'll ever need is here.
http://www.vim.org/tips/index.php -- for tips which have been discovered by vim users -- vim has so many features, not many people know about all of them. But you can try. One of the best tips (Actually it's a summary of a large number of other tips) is
http://www.vim.org/tips/tip.php?tip_id=305 .
The vim reference card (one of them) may be found here :
http://tnerual.eriogerg.free.fr/vim.html . pdf, dvi, html and tex sources are available.
Last (for now), but certainly not the least, vim's online documentation has _everything_. But it's hard to read through everything. The master help commands are, I think,
:help toc
:help holy-grail
Yes, I am a vim addict

, but I do not forsee myself changing to emacs. I've learnt one, and I'm good at it. I don't want to confuse myself. And I don't want to hold Ctrl all the time