Given that it's tax time, I'd be remiss not to mention at least one free tax filing service.  TaxACT[1] allows you to prepare, print, and efile a federal return regardless of your income.  If your adjusted federal gross income was $54,000 or less in 2007, you can also use Free File[2]. California offers CalFile[3] for filing income taxes free if your federal adjusted gross income was $310,837 or less and if you did not have capital gains or losses.   For other states, look here[4].
 
[1] TaxACT
Website: http://www.taxact.com
Author: 2nd Story Software, Inc.

[2] Internal Revenue Service
Website: http://www.irs.gov/efile/article/0,,id=118986,00.html
Author: United States Department of the Treasury

[3] Franchise Tax Board
Website: http://www.ftb.ca.gov/online/calFile/index.asp
Author: State of California

[4] MyMoneyBlog
Website: http://www.mymoneyblog.com/archives/2007/01/free-online-tax-e-filing-options-for-all-50-states.html
Author: http://www.mymoneyblog.com/about-me-about-mymoneyblog