I prefer Barnacle over android-wifi-tether. You can get Barnacle in the Market. I haven't tested it on my Charge, but on my old Droid 1, Barnacle would keep a steady signal when android-wifi-tether acted flaky.
Current phone: Droid Charge @ 1200MHz. ROM jumping, waiting for CM to arrive!
Originally Posted by UBRocked
Just put your phone in airplane mode and tell him you loaded an iPhone 4 simulator on your Droid.