This app tethers your cell phone internet connection to your PC. The connection between your phone and PC is an ad hoc wifi connection.
This app only works with phones that have root/super user access (e.g. the Development Phone). It has been tested and is working for Android 1.0, 1.1, 1.5 (cupcake). Note that the Development Phone now has root access disabled by default in Android 1.5, contact me for instructions on how to enable it.
Here is a few notes about the application...
* To install this application, download it from the market and install it. Click the download link below from your phone.
* To start the tethering just click on the start tether button.
* To stop the tethering just click on the stop tether button.
* Your Wifi will be turned off for this application. If your wifi is on, this app will turn it off when you hit start and then turn it back on when you hit stop. Your wifi will actually be on when this service is running, but in ad hoc mode as opposed to the normal mode, so you will not see the wifi symbol, you may notice your battery drain faster.
* After the wifi tethering service starts, you can connect to your phone from your pc. There will be an ad hoc network with a SSID (wireless network name) of Android, this can be changed in the settings. Connect to this ad hoc network (you may have to enable connections to ad hoc networks).
* As your PC(s) connect you will see them come up in a DHCP clients list below the start and stop buttons.
* You can also enable MAC filtering, so that you can limit what can connect through your phone. To do so, add MAC addresses to the MAC filter list and then select Enable MAC Filtering from the Options Menu
* To add/remove MAC addresses to the filter list, you can either long click an item from the DHCP clients list or you can select the View MAC Filter List from the Options Menu
* This program makes your phone act as an ad hoc Wifi NAT router with an IP of 10.0.1.2 and will give your PC a DHCP lease of 10.0.1.x, you can change these settings
* This app is now released and stable, but if you have any problems or see any bugs post send me an email. Contact me through the market contact info.
* View the licensing page for licensing details.

Visit http://www.androidactivity.com/tetherWifi.html for more details

Screenshots: