Right now I'm using surround.vim
to enclose text in HTML tags, and a plugin that highlights text according to the hex value in the CSS file (e.g. #888 will have gray background in the CSS file).
Are there other useful plugins for web development?
Recommendations
Here is a list of the plugins mentioned in the answers so far:
I've written answers for this question and this question explaining how to get JavaScript syntax checking / linting and source-code browsing / tag-list for Vim using the community-driven jshint.com (which is way better than JSLint IMO) and Mozilla's DoctorJS (formerly jsctags).