Couple more things....

Use FedEx/UPS to your advantage:
If you have a bunch of materials or equipment you need to bring for a meeting, or you obtained a bunch of extra stuff at your destination that you need to get home, don't lug it across the country. Instead, just stop by a local FexEx or UPS store and just ship it. I've even shipped extra clothing items to/from my destination just because I didn't want to carry it.

Clean-out/leave extra's at home or in car:
I clean receipts and stuff out of my wallet before embarking on a trip and leave extra cards out of my wallet that I know I won't need. When I park my car at the airport, I leave extra keys and stuff in the car instead of lugging them on my trip.