itax is a free/open source multi-platform implementation and extension of the Australian Tax Offices(ATO) 'e-tax' software.
phase 1 of this to create a free/open source multi-platform implementation of the ATOs e-tax
phase 2 is to extend e-tax
PhpTax is freesoftware 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.