For those of you who live in crowded metros or high density neighborhoods (apartments/condo complexes) there's a neat wireless ethernet product out on the market that helps you take advantage of your close proximity. The principle of the product is simple: community wireless mesh networking for delivering internet access.
The basis of the network is a router/repeater unit that picks up existing wireless ethernet signals and amplifies it. One of these repeaters is established as the Internet source and is connected to an ISP broadband pipe (whether that's a cable or DSL internet signal, it doesen't matter) The other repeaters simply pick up the signal and relay it so that other users can piggyback and pick up wireless internet access.
For more info, check out meraki.net to find out what it's all about...
For more advanced and enterprising users, one can also be a local ISP host and charge other users for access to the Internet. Anyone who tries to connect to the main signal gets a screen prompting them for billing information for either one-time access or a subscription that is billed periodically. Meraki handles all the billing screens and processing and simply sends a cut of the profits back to the person hosting the Internet service. THAT is what I find cool. I can be my own mini ISP for my neighborhood... or I can simply afford more bandwidth if I am sharing the cost between several of my neighbors.