I can't believe I've only now discovered Happy Tape.
It's Japanese masking tape in the most beautiful colors and patterns. The 10 packs of tape sell for about $36, and the individual rolls sell for about $5.50.
This would work great on presents, favors, invitations, party labels, you name it. It makes me feel creative just looking at it.
Here are some of my favorite tape collections, but check out their site for many more options...