The term 'cross processing' comes from the days of film and chemicals and refers to processing one type of film in the chemicals designed for a different type of film.
A similar effect can now be obtained in SW by changing the different color channels by various amounts. Search the forum for 'cross process' as well as 'urban acid' for different examples. The Urban Acid action from
ATNCentral is pretty popular these days.
http://www.texasphotoforum.com/forum/showthread.php?t=18632
Here is a tutorial on doing the same effect manually using the Curves function in PS or other tools.
http://www.phoeniximaging.co.uk/Tuto.../XProcess.html 