I also have a black silicone case for my Galaxy S. It's smooth, but not slippery. I don't know what the brand is, as I got it from a cell phone kiosk in the mall. So I can only assume it's some generic brand from overseas. But it does the job.
It has openings for the headset jack, multifunction usb jack, camera, backside speaker, and microphone. The volume key and power key is covered, but there's a convex button that goes over the keys, which you can feel and press to activate the associated key.
There's also an opening on the left side, just above the volume key, that exposes an opening. I don't know what this port is for, and it's not stated in my manual. But the manual's picture does show the port. Does anyone know what this is for?
The case itself doesn't add much weight to the original phone. The fit is snug, yet is still easily removable. The texture is really smooth, like a baby's behind. When you hold it in your palm, it doesn't slip or slide, even when it's hot outdoors and my palms/fingers are slightly perspired. There's no sign of finger prints or oily residue after handling. As for the perspiration, a simple wipe with a cloth (or your shirt) dries it off sufficiently.
Dimension-wise, the case adds maybe 1/8th of an inch around the perimeter of the phone, or just a few millimeters. It's still barely noticeable.
Overall, I really like this case and am glad I found that kiosk after my unsuccessful searches at other various department stores (ATT, Verizon, Sprint, Best Buy, Radio Shack, T-Mobile).
feels like it adds a bit weight to the phone aswel
