Just got an inexpensive eBay TPU back cover to use with my tan leather Smart Cover today, and I'm really impressed with the look, and the improvement in handling and grip. The TPU back fits perfectly, as do all the cutouts. I wasn't a big fan of continuing to use the Smart Cover, until I added the TPU back. Here's the back cover I bought, and some pics below:
http://cgi.ebay.com/BLACK-SMART-COV...ultDomain_0&hash=item33669cc6a2#ht_2855wt_972
http://cgi.ebay.com/BLACK-SMART-COV...ultDomain_0&hash=item33669cc6a2#ht_2855wt_972