I can't say that there are many that I haven't tried.
I have done framing, three-dimensional (mainly boxes and ornaments but also pillows and easels/stand-ups), even banners! I can't say I've had rousing success with all of them...I still prefer a professional framer to my own handiwork and getting banners cut right, hemmed and properly lined is a pain I associate with my terrible record with making quilts (many of which have featured embroidery, although not cross-stitch)!
I have never tried using cross stitch on cards (although I have stitched on paper) and don't really see the need for that.
As per usual, I have not stitched at all this month because of my wrist/thumb injury. I am out of the splint and in to strength-building PT for at least three more weeks. I see the surgeon for the second follow-up on October 3. We shall see if the thumb will ever be "nornmal" enough to allow me to hold a hoop again...