I was helping out an extended family member over the phone the other night when I realized he would connect one of his two computers directly to the cable modem, in turn, depending on which computer he was going to use to get internet access.
This struck me as being very odd. Ten years ago, I was using hubs and later migrated to switches and then router/switch combinations to network computers. I just can't imagine what life would be like to have more than one computer in a house and not some sort of network between them.
More scary was that he called me on April 1st, the day the Conficker author(s) decided to freak everyone out. Since Conficker's primary infection mechanism was to exploit a vulnerability in a Windows service and he had just reinstalled Windows on that computer, I was worried he could get infected and warned him about the dangers of doing so.
In this case, a router would have not only removed the "unplug this computer, plug that computer" inconvenience but also have acted as a firewall between his computer(s) and the internet, therefore making it difficult to get infected by worms like Conficker just because your computer is connected to a [hostile] network.
Thankfully, I have an extra router lying around that I'll give him the next time I see him, but seriously, if you don't have a router, go spend $50 on a networking device that doubles as a firewall. Most internet software is NAT-aware these days, so you're no longer trading off convenience for security.