IndexedSearch - when you do searches will show you “Match 2 of 4” in the status line
delimitMate - automatically closes quotes
SearchComplete - tab completion in the / search window
syntastic - automatic syntax checking when you save the file
repeat - adds . (repeat command) support for complex commands like surround.vim. i.e. if you perform a surround and hit ., it will Just Work (vim by default will only repeat the last piece of the complex command)
endwise - automatically closes blocks (if/end)
autotag - automatically creates tags for fast sourcecode browsing. use ,f over a symbol name to go to its definition
matchit - helps with matching brackets, improves other plugins
AnsiEsc - inteprets ansi color codes inside log files. great for looking at Rails logs
solarized - a color scheme scientifically calibrated for awesomeness (including skwp mods for ShowMarks)
Lightline - Improved status bar. Requires patched fonts (installed from fonts/ directory)