Somewhere on the internet I saw a globe that had been transformed with chalkboard paint. I thought it looked amazingly cool so I trolled my local thrift stores and found two globes at reasonable prices.
One of them easily came free from it's metal support. The other one did not. I sanded both globes, then wiped them with a damp rag. (Both globes did have bumpy mountains on them, which I didn't really worry about). For the one that was loose from it's frame, I set it on a long screw supported by a brick while I spray painted it with chalkboard paint.
For the one that was stuck in it's metal support, I blue taped the heck out of it and covered the support frame with newsprint.
The paint can said to apply two coats, but I did at least three. I made sure to flip them over so the bottom hemisphere got well covered as well. I did have some over-spray on the metal support that I thought I had blue taped so well, but it easily came off with nail polish remover.
Now I need some chalk!