Question: I need to encrypt social security column in a list. What are my options?

ps: Did not find Encryption in the Tags. 

Actually, looking for something like this (Column Level Security, but non commercial solution)
<http://store.bamboosolutions.com/sharepoint-column-level-security.aspx>

This may be new topic or a topic no one wants to talk about.

Answer: 
You can use Transparent Data Encryption for the entire SharePoint Content database.
You can create custom secure field. see this codeplex solution: <http://cryptocollaboration.codeplex.com/>

FYI: I have seen issues with custom fields (almost all the time) either with jquery or 3rd party or nintex. So that's something you will have calculate when implementing custom fields.

Good Luck