Freezer paper is also a staple for applique. You can trace a design through it easily and mark it on the paper side. The plastic side will adhere to fabric when ironed on w/ a cool iron, but easy to remove, and often use again. You can find it in most grocery stores.
I use old CDs, in both the standard size and the minis as a circle template. The standard fits very nicely on a charm pack square (5").
I know I've got other clever re-uses, but none springs to my sleep deprived mind at this moment.
RST