The two wallpapers I like most on Linux. Both are translucent and can be set to any colour. The first is SVG, the second PNG.
“Tentacles” was part of gnome-backgrounds for quite some time. It was removed in GNOME 2.24.
I have never used translucent backgrounds in Windows or OS X, and have no idea if or how it is possible. If you know, please leave a comment.
- The colour palette of the Tango Project.