Here are the plugins I'm currently using as well as some vimrc mappings to make things a bit easier.
Plugins
Pathogen is an essential vim plugin for every user. It helps keep all the plugins you need organized within their own directories. This makes it much easier to uninstall plugins at a later time, since your plugins don't all live in the same tree. Pathogen will handle adding everything together at runtime.
Command-T adds the popular textmate feature that makes it easy to open files.
Snipmate gives vim the power of textmate like snippets.
Sparkup adds zencoding to vim to make it faster and easier to write HTML.
NERDCommenter makes it easy to toggle commented blocks of code.
Syntastic adds syntax checking to lots of different file types, and if vim has signs support enabled, you get markers to the left of your line numbers telling you where your errors are.
.vimrc config settings
Encode/Decode HTML to HTML Entities (Great for writing documentation)
"EASILY ESCAPE OR UNESCAPE HTML
function HtmlEscape()
silent s/&/\&/eg
silent s/</\</eg
silent s/>/\>/eg
endfunction
function HtmlUnEscape()
silent s/</</eg
silent s/>/>/eg
silent s/&/\&/eg
endfunction
map <silent> <c-h> :call HtmlEscape()<CR>
map <silent> <c-u> :call HtmlUnEscape()<CR>
Toggle Relative Line Numbers (new VIM 7.3 feature)
function! g:ToggleNuMode()
if(&rnu == 1)
set nu
else
set rnu
endif
endfunc
nnoremap <C-L> :call g:ToggleNuMode()<cr>
Highlight unwanted whitespace
"HIGHLIGHT POTENTIALLY UNWANTED WHITESPACE
highlight BadWhitespace term=standout ctermbg=red guibg=red
match BadWhitespace /[^* \t]\zs\s\+$\| \+\ze\t/