Update: I just found another such list of open source programs specifically for graphics applications, including screenshots. This is actually split over two pages.
http://www.snap2objects.com/2007/07/20/45-best-freeware-design-programs/Update 2: And here is another list.
Other related posts:
UK government supports open source
25 open source projects for software development
Dabbling in OpenSolaris
Comment by Clement, on 24-Sep-2007 23:11
Great addition to the list. Keep bring them. Would you mind if I add the list that you have generated so far to my site. Of I will link up to your site
Comment by chakkaradeep, on 24-Sep-2007 23:59
Have a look here too - http://www.opensourcewindows.org/