I am probably very wrong on this, but there was a short segment on Wi-Fi yesterday, and I swear they said you could buy a device for ~$100, and use it to get on the web without wires, and without needing an ISP.
You always have to have an ISP - somewhere in the loop.
A Wi-FI connection doesn’t take the place of an ISP, it takes the place of a network hub/router and the wires.
In other words, you plug the Wi-FI hub into your DSL/Cable modem, then a card into your computer and access the Web/e-mail wirelessly.
Now, if you’re someplace that has a “hotspot,” or a Wi-Fi connection, you may be able to pay them to log on to their connection, most likely by the hour.
But it does not take the place of DSL/Cable/Dialup. You have to hook it to an ISP for it to work.
See How Wi-Fi Works for more information - just remember to turn your pop-up stopper on - lots of pop-ups on this site.