Few years ago I used a lightweight IDE called “Sublime Text 2″. And one of the most compelling features of it was an ability to switch between files by hitting Ctrl + P and typing in a part of the file name.
This is exactly what ctrlp.vim implements in vim. Usage is extremely simple: install the plugin, hit Ctrl + P, type a part of the file name, select a desired file and hit Enter. You can use arrow keys or Ctrl + J and Ctrl + K to navigate between suggested file list.