Before going on significant trips, I usually freak out over camera memory: do I have enough memory cards, and do I have a good enough backup system with me.
With memory cards becoming so common, one solution is to loan/borrow cards from friends.
A friend is going on vacation, has an older Kodak digital camera, wanted to buy a bigger memory card, but was also in the market for a new camera. I suggested that it didn't make sense to buy a new CompactFlash memory card when the new camera most likely would take a SecureDigital card. Then I realized, I've got lots of CF cards laying around. So she'll come by one day, and borrow a few for her trip.
One of my daughters is on a school trip to Korea. I had figured that a 256MB SD card would be sufficient. After all, my other daughter went on a school trip to France for two weeks, and came back with room left on her 256MB memory card.
Back in Korea, however, #2 daughter reports that she has just 30 pix left after six days. So I told her to buy another card, which she did. Later, I realized she could've taken along #1 daughter's memory card; it would have fit.
She also reported that she and other members of the school group were cooperating in taking photos. If two people got a picture of something,there was no need for the third to also take the same picture. When they get back home, they'll swap CDs of their photos.