If you're a fan of NERDTree, patched fonts, and vim-airline, then you might like Ryan L McIntyre's vim-webdevicons (GitHub: ryanoasis/vim-webdevicons, License: MIT). It adds icons for web development-related file types, and includes things like an image icon, logos for programming languages, and even some logos for templating languages.
You can configure whether or not icons appear in NERDTree or airline individually, and you can also configure the amount of space glyphs get. There are character mapping settings that let you change the default character, or use custom characters as well.
In my experience setting up patched fonts takes a bit of extra effort. Ryan links to nerd-filetype-glyphs-fonts-patcher which is a Python script that patches any font.
If this is all new to you and vim-airline just blew your mind, then you might want to check out the vim-airline FAQ if you have any trouble setting things up.