With ATT Tilt you can turn it into a Wifi router with some software paid or free.
Here is a commercial software that you can buy: http://wmwifirouter.com/
Here is a big thread with some info on hack together a free solution: http://forum.xda-developers.com/showthread.php?p=4175565#post4175565
Or you can use a nice little free program call: ICSControl
Note: you have to follow these steps exactly for it to work!
Here are the steps on how to use this utility:
1. define WIFI connection and set WEP
2. turn on WIFI and connect
3. start ICS control then set
a. public interface: cellular line
b. private interface: TNETW12511
c. Set Private IP 192.168.2.1
d. Auto connect to: media net
e: start ICS