The issue of tax havens recently came up in discussion with some coworkers. The idea is that many companies have multiple subsidiaries that are shell companies, and wouldn't really be interesting for the scope of this project. The Stop Tax Haven Abuse Act bill that is in congress now has a good list of tax havens that we could use to filter out the "shell" companies, so that the mashup we create can distinguish between valid business entities and companies that are just being used to hide money from the IRS.