You don't need photoshop or anything, just take two photos from slightly different angles (I choose a single point on the centre of the viewfinder (crosshairs) and just make sure the second photo is pointing at the same bit).
Then the program does it for you. It's freeware and takes less than a minute to download.
Source:
http://rosset.org/graphix/anaglyph/zanag_en.htm