Make your own big font coasters
I just love this concept from Evil Mad Scientist: make your own drinks coasters based on various characters in a range of fonts.
You can read up on the whole process, but basically the idea is to blow up fonts to large point sizes, print and then cut them out of some kind of material (MDF, cork, plywood, etc.)
It’s great for showing off fonts in really big sizes, though, as with using old CDs for coasters, having holes underneath the glass or mug might not be a good thing.
Having said that, I think the at sign works really well, closely followed by the hash and the asterisk.