[fpgeek]

Someone has already covered tethering, so I'll just emphasize there are plenty of other useful things you can get by enabling "Unknown sources" without rooting: other app stores (Amazon [noted upthread], GetJar, MiKandi, ...) often with their own exclusives, software under development (Swype Beta, Mozilla's Aurora and Nightly, ...) and so on.

Separately, if you managed to buy a Thunderbolt from AT&T you have much bigger problems than getting tethering working. The Thunderbolt is a Verizon-specific CDMA/LTE phone that doesn't support any of AT&T's networks (AT&T's LTE is on a different band).

[gcb]

yeah, the thunderbolt wasn't mine :) had no idea which operator locked it. but it was locked beyond hope.

and i wasn't saying 'non-google-store-sources-aka-unkown-sources is a bad thing. i was just saying it's not enough to 'do what you want' with your device.