Nerd Tree is indeed a good one, and I'll add to this vimfs, which isn't a Vim plugin but rather a CLI file system browser with Vim bindings. I hardly ever actually browse my file system (zfs, grep, and locate do all of the work for me), so I'm not sure how much mileage one can get out of this (especially compared to something like Midnight Commander).
g$ - move cursor to last displayed character of line
Tx - move cursor backward and to the right of the first occurrence of x (reverse of tx)
And get started with split views:
^ws - horizontal split view
^wv - vertical split view
^w{h,j,k,l} - move to window in respective direction
Some decent scripts to get started with:
minibufexpl.vim: http://www.vim.org/scripts/script.php?script_id=159
surround.vim: http://www.vim.org/scripts/script.php?script_id=1697
More of a full-fledge suite, a frontend to a head{ed,less} Eclipse server: http://eclim.sourceforge.net