Check out Resources for some good ideas - here's a link with the search for acetate:
Splitcoaststampers - Resources
I like the acetate and tissue technique a lot. I've also done the glitter stained glass one and the magic card. I like the look of cards made using acetate as a base, but have only made a few.
Something that I think isn't listed there is stamping an image on one side with StazOn and then colouring from the back with alcohol inks.