Are you thinking you’d like to have cable or DSL connectivity without the cable or phone bill? Do you live in close proximity to a number of wireless neighbors? Here’s what you could do: hook up a Linksys WET-11 bridge.
 
Plug the WET11 into your computer with a standard CAT-5 ethernet cable and you’re good to go. The bridge detects any available wireless network transparently. Your OS just acts like you’ve joined a LAN, but it’s the World Wide Area Network. Seamless.
 
ODDLY, the Linksys WET-11 is no longer on the market. Not so oddly, they are a hot item on Ebay.