What to fill a roll of film with?

At the moment I've had a roll of film kicking around in my SLR for some length of time now, and I'm debating how to fill it (as it would be nice to get the stuff that's currently on there developed).

Currently I've got a Kodak Easyshare CX6330 on an indefinite-length loan from a roommate (and he, in turn, is borrowing my MP3/CD player), but it still would be nice to get some digital SLR gear one of these days. I just can't decide between Nikon and Canon at this point - I currently have Nikon gear, but Nikon has in recent years done some stupid things. Nikon seems to have better build quality on their consumer-level DSLRs, but Canon has a lot more models to offer.