It may not always be the most reliable, but that iPhone in your pocket is a viable internet connection, anywhere you go. So use it! The Nexaira BC2 will turn the thing into a full wireless router, no jailbreaking required.
The $190 BC2 is a full-fledged 802.11 B/G/N router—just stick your tethering-enable iPhone into it via USB, and you'll have up to 200 feet of wireless coverage for all the rest of your devices. It won't replace your home connection—3G data only, of course—but if the cable's ever out, or you find yourself traveling, the thing could be handy in a pinch. [3Gstore]