1) Patch a few pairs for when you're doing scruffy work (and save some of your nicer pants from getting worn out as quickly).
We will be keeping one or 2 pairs for this purpose.

2) Patch them in really artsy/cool/creative ways and make a fashion statement even when you're dressed down.
BTDT in college - I was known for my crazyquilt patched jeans - and these are M's jeans, and he's not likely to wear funky creatively patched jeans. They actually end up requiring quite a bit of maintenance to keep the new holes under control, too.

3) Make one into a handbag -- I see them being sold in stores, so that one's actually trendy...
A possibility, though I don't know if I would actually use said handbag. I did recently recycle a worn-out pair of M's shorts into a purse for TRex.

4) Cut them into long skinny strips and make placemats, or a throw rug. Usually done by cutting the strips about 2" wide so that the raw edges can be turned in on themselves.
This is the kind of thing I've been thinking about, but again it's a factor of time. Must do a bit of research on strip/braided things.