hsetroot is a tool which allows you to compose wallpapers.

It has a lot of options like rendering gradients, solids, images but it
also allows you to perform manipulations on those things, or chain them
all together. You could use one standard background image for instance,
and use tint to make it fit your current theme. And yes, of course it
is compatible with semi-translucent applications like aterm and xchat.
