Like many people who aren't able to get DSL, I use mobile broadband. Typically, at least in Ireland and the UK, you are forced to purchase a modem with your contract. What if you want other devices in your house to use this broadband and you don't want to fork out several hundred wing wangs for a mobile broadband router like the Novatel MiFi when you have a perfectly good modem and wireless router already? In Ubuntu you can setup the modem-connected machine as a robust router/firewall using the in-built Network Manager, Firestarter, and optionally, Gadmin DHCPD.
My family is hooked on Windows. I’ve thought about trying to coerce them into switching to GNU/Linux, but the very thought of what I’d have to put up with for the next year just makes my head ache. I’m not talking about software maintenance issues. I’m talking about trying to defend my position time and time again as they complain that they can’t run their favorite games or applications. Telling them to change their favorites is like spitting into the wind—it’s sort of masochistic.