iTether uses a some fancy HTML5-based software to tether your iPhone. It’s not entirely clear how it does it, but users create an ad-hoc network from their computer then visit the website on their iPhone.
The video above shows iTether at work. It just makes clever use of HTML5 to get the job done. It will run you about $30 a year, and the first year is $15. It’s also worth noting that AT&T somehow knows when people are tethering, and will usually just switch them over to another plan and sign them up for tethering at the regular price.
Check it out at Tether.