On any given project at work, I will always end up opening 3-4 windows (and even more recently, the NERD Tree sidebar, which is a plugin I recommend everyone get) and I get sick of having to press Ctrl+W and then h, j, k or l to move to the next window. It's one of my most used key combinations and it needed to be shortened.
I wanted to just type Ctrl+[hjkl]. So I added this to my .vimrc:
nnoremap <C-h> <C-w>h nnoremap <C-j> <C-w>j nnoremap <C-k> <C-w>k nnoremap <C-l> <C-w>l
And that's it. Easier window navigation with a quick vimrc addition!