These are some desktop backgrounds made by me with the GIMP. Most of them are at 1280x1024, which is the resolution I use, but some are available at other sizes.
This background is almost entirely blue. It gives a general impression of a tunnel.
Download: blue (1280×1024)
This background is mostly light green, but with a touch of light blue. It has a pattern of small round shapes, which gives an impression of leaves or perhaps The Matrix.
Download: light green (1280×1024)
This background is entirely light blue. It has similar patterning to the light green background, but with additional larger spots.
Download: light blue (1280×1024)
This background is almost entirely bright orange. It has patterning which gives a flowing appearance. Amazingly, it doesn't overwhelm most desktops.
Download: lava (1280×1024)
This background is red and purple. It has patterning somewhat similar to the light green background.
Download: purple/red (1024×768)
This background is just a recolored version of the light blue background, but the result looks a bit flatter.
Download: purple (1280×1024)
This fairly simple background is mostly purple, but with thin light blue lines radiating from the center.
Download: purple/blue (1280×1024)
This background was made on a request which I freely admit admit to failing. It's still fairly nice, though.
Download: silver (1024×768)
This background is mostly red, with black rings going through it.
Download: red (1280×1024)
This background is mostly yellow, with some light orange. For some strange reason, it is divided in several places with bands of white.
Download: yellow (1280×1024)
This relatively simple background is mostly lime, but with a hint of blue.
Download: lime 800×600, lime 1024×768, lime 1280×960
This background has bright orange, yellow and red, giving a firey appearance.
Download: fire 640×480, fire 800×600, fire 1024×768, fire 1280×960, fire 1600×1200
This background is mostly green, with some yellow and red mixed in.
Download: green/yellow 640×480, green/yellow 800×600, green/yellow 1024×768, green/yellow 1280×960, green/yellow 1600×1200
This background is mostly gloomy-looking blue and green, but there is a small bit of colorful red.
Download: gloomy