Ditto on the blue twisty rotary blade sharpener. Unfortunately, I also got sucked into an electric sharpener with stones ... haven't been able to get it to work either.
Bought a rotating cutting mat; don't find it useful
Printable "fabric" for labels, from Joann's. It's like vinyl! Not pleasant to touch at all.
And last, I bought an attachment for my Janome that's supposed to let you sew a perfect circle. It was very expensive for what it is, and leaves kind of a big hole in the fabric at the pivot point. Lots of folks have talked about using a thumbtack taped to the table with a piece of cork; that would probably work better and will be what I try the next time I need it.