I have the Sena black ultra-slim pouch and its been great. Good protection, stand by magnet to shut down device when you put it in; slim and you could slip it in any pocket with protection.
I have had Sena cases since my Palm 650 days. Right not I am using the Palm 650 side pouch with a Case Mate skin. No sleep funtion but a really good combo.
Sena cases are available at senacases.com.
The Sena case is nice but I ended up returning mine since you need to push the Bold out from the bottom. What ended up happening to me was that I kept hitting the battery door release button as well at the same time.