If you have a WP7 Samsung Focus from AT&T you can use the device as a tethered USB modem.
1. Open phone dial pad
2. dial “##634#”
3. Hit send, this will install a diagnostic app in your application directory for future access.
4. When the diagnostics interface comes up dial “*#7284#”
5. You will see the “Micro USB Test” screen options for Zune Sync, Modem tethered call and modem USD Diag. Select modem tethered.
6. Restart phone
7. Connect your phone to your computer via the USB
8. The drivers will be installed via the device USB.
9. Locate the modem on your computer and change the settings to prompt for user name and these values;
user name WAP@CINGULARGPRS.COM
****WARNING; USE THIS HACK AT YOUR OWN RISK****