I heard about this in a magazine a while back, and just came across the link again (from Neil Gaiman's blog.)
http://www.blacksocks.com/ "The sockscription - there is no easier way to deal with your sock angst."
Basically, you sign up for a 'sockscription', and they send you three pairs of black socks every few months. You can choose 2-, 3-, or 4-monthly intervals, depending on how many socks you tend to lose a year. They also do Corporate Sockscriptions and Gift Sockscriptions, and if you sign a friend up you get a free pair of socks.
They also have a very weird Flash animation.
I'd subscribe if it didn't cost £45 for 9 pairs of socks o.O