Update: 10/28/2013 – A lot has changed, I would not try this strategy anymore. Use at your own risk.
I am not a fan of directories. They don’t feel like something Google would want you to do, but – they aren’t against the rules (yet) and they are a valuable provider of anchor text, so I’ll use them. Many agencies have coveted list of free and cheap directories that they will submit their clients to, but since Google has deindexed numerous directories in the last year you can’t rely on dated internal lists of once valuable directories.