Update: 8/2 - it's gone yet again. Hope you got it while it was available.
Yesterday, NullRiver released NetShare (App Store), a $9.99 application that lets you use your wireless signal on your iPhone on your computer. A process knows as tethering, even if it's done over wireless.
That application was mysteriously pulled down by Apple late yesterday. According to TechCrunch, the application has reappeared in the App Store. Tethering is something that most smartphones can do but is something that carriers generally charge extra for.
If the application stays up in the store we'll post a review soon.