Add AJAX list filter

I tried searching for something that's an example of what I'm talking about, but I couldn't find anything, so hopefully this description will be somewhat clear.

I propose adding a textfield onto the modules list (and probably also the issue tracker) that lets you type in stuff, and as you type (or after hitting Enter, for performance), would interactively filter the list by nodes that had that string in the title or body.

If I come across a site that has this functionality, I'll post a link here. I know I can't be the first person to have thought of this. :P