It's cheap, it's fun and the possibilities are endless. I don't know when I'll be able to work on this project, but hopefully in the near future. I think this would be a terrific and inexpensive house-warming gift.
If you have never worked with plaster before, check out these directions.
Here is a fun little planter that looks like a Row-house.
The photo above is from here (a special note.... only the masks are made out of plaster, underneath is a cheap plastic pot that has been painted white).