Here’s a small and handy TextMate bundle, Multiple Arbitrary Simultaneous Carets.
I’m not sure if I’m using the best TextMate Bundle terminology, but this is how I would describe it: it lets you insert multiple cursors and then enter text at all of them at once, just like the behavior that is built into traditional pre-structured TextMate Snippets.
That page also has a screencast demonstrating its capabilities. Check it out.
