I use Sublime Text 2 all the time. I'm also give files all the time which need tweaking before they can be used. Yesterday someone sent me a bunch of e-mail addresses separated by semi-colons, but I needed the content instead to be separated by new line characters. Here's how I did it.
Open the file
Choose Find->Replace.
Then select the 'Regular Expression' button at the bottom left of the screen.
In the 'Find What:' field type your character. In my case it was the semi-colon.
In the 'Replace With:' field type \n
The click the 'Replace All' button.
Hey presto!