STM's new Skinny case is one of the lightest cases out there. It has fabric-covered polycarbonate rear shell, microsuede on the inside, and integrated magnetic sleep/wake front cover that's also covered in fabric.
The clasp keeps the cover closed and also helps convert the case into a stable two-position stand. This is another good one from STM that's available in several colors.
Note: This case isn't quite shipping yet, but I did test out early samples of the product.