Labeling food units

For all you folks out there who make large batches of stuff and then divide it up for storage, to eat later:

How do you label the containers?

Me, I'm freezing and refrigerating big piles of soup, and I'm sticking masking tape on the lids of the containers and then writing the contents and date on the tape. When I eat the stuff, I peel off the tape before washing the container. This masking tape thing seems like a pain in the butt, but I'm not sure I can come up with anything better. Grease pencil? Writing directly on disposable bags (vacuum-sealed or whatever)? What do you folks do?