Add this to the list of clever ways to use a mason jar: DIY hand-poured candles. You can make them in any color or scent you want - and - they make great gifts! You can buy the wax here, and various scents here.
Jen from Something Turquoise has an incredibly detailed (and beautifully photographed) tutorial that explains everything you could possibly want to know about making your own poured candles. She even covers the best way to clean up after an afternoon spent melting wax and all that good stuff. Head over to Something Turquoise and check it out!