June Tailor Shape Cut is a slotted ruler (larger is 18", smaller is 12") that allows you to cut strips by folding your fabric and slicing in the slots. They are marked for 1/2" or 1/4" (1/4" is a little tricky to get the hang of, but there are directions and a video) and the slots are 1" apart up to 12" or 18". You square up the end of the folded fabric and then follow the slots for 2" or 2 1/2" strips, etc. I used it to make piano keys of all different widths, just sliced until I ran out of fabric, made alot of them! Easy to use, no finger cuts, lots easier than aligning the ruler each and every slice!
http://www.junetailor.com/shapecutplusvideo.htm