RadTech Gelz for iPhone
I confess that in the almost three months I've been using the iPhone, I've used it almost exclusively without the addition of a case. Mostly that's because the phone is just so slick, you hate to have cover it in anything, no matter how thin.
RadTech's Gelz ($9) case is a silicone skin that measures just 1.2mm thick. The rubberized material is slightly slick to the touch, and it fits around the iPhone like a glove, with openings for the screen, camera, headphone jack, dock-connector port/speaker/mic, and the control buttons.
From an aesthetic point of view, it's hard to argue that the iPhone isn't much prettier without the addition of a case. Everyone I knew who saw the case opined that it was garish (I tested a bright blue model), with one going so far as to suggest that it screamed "Hey, everybody! I've got an iPhone! Mug me!" Having tested plenty of cases for the iPod over the years, I'm not convinced that it's any worse than most of silicone skin-style cases, but the point is worth noting.
On the protective side, the Gelz case will keep you from scratching up the back of the phone, or the chrome ring around the screen, but without buying additional protection (RadTech charges $10 for an adhesive film), the screen itself is vulnerable. As that's the only part of the phone that I've actually nicked, that mitigates the case's use somewhat.
Unlike some other silicone cases, the Gelz leaves openings for the volume, sleep/wake, and silent/ring buttons. Because these buttons are even more flush with the iPhone than the thickness of the case, it can make it annoying to hit the controls. Fortunately, the case is stretchy, so you can sort of wiggle your finger in where necessary. The texture of the silicone makes the iPhone grippier, which is nice if you constantly feel like it's about to slip out of your grasp, but is somewhat annoying when it comes to getting it in and out of a snug pocket. Also, I found that the case attracted its fair share of lint and dust, and sometimes trapped particles on the phone itself; nothing that didn't come off with a good wipe when I took the phone out of the case, but it was a little annoying.
Overall, the RadTech Gelz probably isn't any worse than any other silicone case on the market, and it's likely cheaper than many. You may want to opt for something other than bright blue, though: RadTech also offers the Gelz in pink, white, black, green, and orange.--Dan Moren
RadTech Gelz for iPhone