Nerdtree is one of my VIM essentials, but I was always annoyed that it took so much space in the screen. Since I use a vertical monitor, I barely get 80 characters to work on. I recently found that this is easily fixed by adding a configuration to .vimrc:

let g:NERDTreeWinSize = 20

Sometimes, when I was browsing through the folders I actually wanted to be able to make it larger so I could see the complete file names. This is also easy to achieve. Move your cursor to Nerdtree and toggle it using:

shift + a
[ productivity  vim  ]
Vim command line mode
The Vim statusline
Spell and Grammar checking on vim
Setting the search directory for Ctrlp vim plugin
Disable expandtab in Vim