If you don't like the shading or tinting effects that eterm has built into it or they are too slow for you (eterm is really a bit slow actually), you could try the following to have backgrounds or images in your terminal emulator. Choose a background you want to modify, open gimp or whatever application you are using for editing your graphics, open the background. Now if you are using gimp (and you can use a bit) make a new transparent layer on your background, do some effects (gradients or waves are cool) on it, and then take the opacity down until you like it (and you can see the background layer through the upper layer). Now save your background, remember its name and open a shell. If you want to use this background in eterm, use the -P option to specify the image's location, and --viewport-mode which is like having a transparent eterm using the image you specified as your background. So if you have created a blue to black gradient on your image and you are using viewport-mode (with the same image in eterm and on your background) it will look like a transparent eterm with a funky blue to black gradient on it. Try it if you didn't understand this fully, you'll be happy with it, because it will look cool and it should be faster than using a transparent terminal.
Thanks to http://q3test.2y.net/~moyix/etweak.html