TaxGeek

It looks like there’s finally an open source option for US taxes:

TaxGeek was written in response to the demand for an Open Sourced US Federal Income Tax program that works on GNU/Linux based computers. It is by no means complete, but may serve to help you file your 2006 income taxes if your life is not *too* complicated.

Alas, my life is too complicated, and I no longer do my own taxes. Hopefully this is useful for someone else, though?