I currently use a Speck clear hard "plastic" case on my Curve. I like the look of leather better especially if fits tightly, provides protection and is fairly simple. Anybody using a leather case that they are very satisfired with?
Vaja cases are pretty pricey, my buddy has one looks like its doing a good job. I just got the blackberry leather belt clip with my BSE and its doing good too.
I just use the OEM top-loading pouch. I've only been using it about a week now, but it's been great. Easy to get the phone in and out, but still keeps it protected and isn't too bulky that it gets in the way. Otherwise, I just use the protective slip pouch that came with the phone and throw it in my pocket.