DetectSyntax is a plugin for Sublime Text 2 that allows you to detect the syntax of files that might not otherwise be detected properly. For example, files with the .rb extension are usually Ruby files, but when they are found in a Rails project, they could be RSpec spec files, Cucumber step files, Ruby on Rails files (controllers, models, etc), or just plain Ruby files. This is actually the problem I was trying to solve when I started working on this plugin.

For more information, see https://github.com/phillipkoebbe/DetectSyntax.