You can store cupcake liners in mason jars. So colorful!
Lilacs look lovely in an old, blue-tinted jar.
How about a button jar?
For candlelight, fill the bottom of your jars about 1/4 to 1/3 full of rice, sand or coarse salt; then pop in a candle.
You can serve lemonade or iced tea in mason jar drinking glasses.
Make a pin cushion and sewing kit, using mason jars.
And finally, how about this clever wreath for the yard, made out of jar rings!