Xcode (the Objective-C IDE) has a great feature where you can simultaneously edit all occurrences of a string at once within a given scope. This is really handy when renaming method parameters or variable names — it saves a lot of time, and prevents any of the mishaps that Find and Replace and introduce. This would be a great addition to Sublime Text 2...
http://sublimetext.userecho.com/topic/117733-edit-all-occurrences-of-string-in-scope/
A simple feature, but one I sorely miss. Would be great either as a built-in feature or as a plugin.