What I do is use an HTC Windows Mobile device as my primary device and which has a cell signal, and use a wi-fi router on the phone to share its EV-DO to my other wi-fi devices.
What's that? An iPhone? Running Safari and obviously online in the middle of nowhere? No, just an iPod Touch, getting its EV-DO using the wi-fi router in my other pocket. And I saved $75/month.