So I guess the modern equivalent of the vanity email address is the vanity URL shortener. I registered ian.lc because it was available and cheapish and because bit.ly's links keep getting longer and longer.
I tried both Google's and Bit.ly's BYO domain shorteners and didn't like them at all. Google forces you to use a subdomain and Bit.ly uses the same namespace for all shortening domains, so all it really offered was vanity, not improved shortness.
After a couple of wisely aborted efforts to write my own I just installed YOURLS, a simple, straight-forward, extensible URL shortener. Like all useful internet software it's all PHP and MySQL so it took virtually no time to deploy - unzip, create database, edit config file, reload.
There's a pretty good WordPress plugin that shortens a link and then posts to twitter that I'm experimenting with as a way to encourage myself to make longer than 140 character posts. Let's see how that goes.