From past cars I've had, the obvious thing that springs to mind is the thrust bearing. It can rattle quite happily for a long time but of course it will eventually cause snags. It is cheap to replace, but only if you're willing and able to get in and do it yourself. It's also a good chance to have a look at the clutch a bit closer. Dirty hands time I'm afraid!
Cheers
Ken Chapman
April 2007