The NERD tree : A tree explorer plugin for navigating the filesystem
http://www.vim.org/scripts/script.php?script_id=1658
Commands
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:NERDTree Open the NERD tree
o Open selected file, or expand selected dir
go Open selected file, but leave cursor in the NERDTree
t Open selected node in a new tab
T Same as 't' but keep the focus on the current tab
<tab> Open selected file in a split window
g<tab> Same as <tab>, but leave the cursor on the NERDTree
! Execute the current file
O Recursively open the selected directory
x Close the current nodes parent
X Recursively close all children of the current node
e Open a netrw for the current dir
Source: http://my.opera.com/subjam/blog/vim-tips