I've actually been gathering mason jars and overpriced drink bottles and such to put together small terrariums. The thinner milk bottle-like ones are only big enough to put in a little moss, but the bigger ones I'm hoping to fill with small cacti and - well, more moss. Then I'm going to do the ultimate nerd thing and put in gachapon anime and pokemon figurines. redface It's the only way to have plants in my home. The cats think everything that's green is their personal salad, and the jars will protect the plants.
You might put some sand in the bottom and wedge tea lights into the sand, then wrap a little wire around for decoration. That would only be beautiful for a few hours, but it would make one hell of a summer party decoration. Imagine two or three at the table, a few more on a buffet (even if it's just a card table set up with a tablecloth over it ;D), and if your friends are like-minded crafters, sending one home with each guest as a memento.