Ideally, when I leave my computer I set my limits to zero, and make them sensible again when I come back. Usually, I forget to do this though.

Why not have the option so that limits are removed if the keyboard/mouse haven't been touched for a certain amount of time (like a screensaver)

I think this makes a lot of sense, since when I'm not using the computer I don't need to leave spare bandwidth for web browsing, email etc.

You're talking about speed limits right? And you want some bandwidth to configure for when there had been no action on the desktop? I dunno, up to George but as always, he already is busy with other stuff.