Case-Mate's latest iPhone 3G case is Vroom ($15), an affordable rubber case designed to look like a car tire. Similar to Treadz, an earlier case from iFrogz, Vroom has treads on its bottom, leaving a hole for the iPhone 3G's camera; it has a nicely proportioned bottom hole and small ones on the top and side, with protection for the volume and Sleep/Wake buttons. On the flip side, it picks up dust pretty easily and exposes the iPhone 3G's chrome…
