TaxGeek is a Mozilla-based US income tax program that includes Form 1040, Schedules A, B, C, C-EZ, D, E, K-1 (1065), SE (Short and Long), W2, Form 8880, Form 8863, and Form 2441 with access to most other files as PDFs.
PhpTax is free software to do your U.S. income taxes. Tested under Unix environment. The program generates .pdfs that can be printed and sent to the IRS. See homepage for details and screenshot.