In vim, there is this amazing plugin called command-t, that lets you fuzzy-search through all the files in your project. We have a fairly large rails app with a ton of files
A github rep for my concoction is here: https://github.com/lewang/anything-project-files
I added a few more anything sources so that anything-project-find can be a drop-in replacement for "C-x b". So the idea is when you hit "C-x b" you are completing against existing buffers, recent files through recentf (personally I hack it to use "session.el" instead, but it's a small diff), files in current dir, files in current project. I find it pretty handy.
I've used this for a while, but it's not well tested, so please report any bugs you find.