I'm LOVING my invisibleSHIELD (theinvisibleshield.com). It's an absolutely invisible cover, provides scratch protection better than a soft/hard case. I'd highly suggest it.
I might have to try the invisible shield. Otherwise, I'm a huge fan of Vaja cases. Total quality - great leather smell (weird I know) and a rounded edge factor that compliments the iPod perfectly. They're working on their stunning iVolution cases for the Nano and 5G iPod right now.