Well I keep all mine on disk. :blah:
But I should really delete about half straight away.
Yeah, I actually 'keep' the majority of what I shoot on disk but it's not worth much of anything. I shoot raw+jpg now and out of 200 pictures from one day I'll separate fifteen or twenty at the most that I want to run through photoshop. I'll go back in a few days and see if anything else catches my attention, then delete all the raw files. This way I'm only keeping the smaller jpg's (I'm a digital packrat!).
So anyway, I guess by keep I mean its something worth printing larger or displaying in your online gallery etc.