On multipitch descents: If the middle of the rope has no mark or has worn off, just mark it with chalk on the first rap and re-chalk it every 3 raps or so.
Alpine rope systems: Get yourself a thin 60 or 70m lead line, 60 or 70m of 6 or 7 mil cord, some rap rings; learn the proper knot-blocks to use, and the intraciacies of the system. Very light, very versatile.
Windscreen: use a laminated extra map as your windscreen for your pocket rocket. Secure the side with duct tape and make sure you have a back up.
Snow climbing: use a picket daisy'ed to yourself as a second tool on easier snow climbs (NF of Shuksan, NF of Buckner, etc.).