Culled dead links and fixed URLs on 29 June 2013. If any links in this list are invalid or lead to placeholder pages, please let us know by sending an email to cyburbiaforums (at) cyburbia (dot) org.
The Gimp (http://www.gimp.org) - GNU Image Manipulation Program. It's a poor man's/woman's Photoshop; it's notorious for having an awkward interface, but it does just about everything the Adobe program does, and for free. Linux, FreeBSD, Windows, Mac OS 10.
Gimpshop (http://www.gimpshop.net) - The Gimp with a user interface that resembles Adobe Photoshop. Mac, Linux, and Windows.
Irfanview (http://www.irfanview.com) - Good lightweight freeware image viewing program. Resizes, optimizes, and converts images, and sets transparent GIF colors. It can also capture a screen image or program window, and save it to a file. The quality of resized and saved JPEG files leaves a lot to be desired, even at higher quality levels. Windows only.
Paint.net (http://www.getpaint.net) - Image and photo manipulation software designed to be used on computers that run Windows 2000 and XP. It supports layers, unlimited undo, special effects, and a wide variety of useful tools.
PhotoPlus (http://www.freeserifsoftware.com/sof...us/default.asp) - Image editing software that enables users to create, manipulate, and enhance photographs, bitmap graphics, and web animations. Windows only.
Pixlr (http://www.pixlr.com/editor) - Online image editing tool. From the site: The pixlr services is built for both non-professionals, the users that have basic editing needs like editing web images to be posted on social networks like Facebook, Myspace Bebo, image sites like Flickr, Fotolog, Photobucket etc.