A fan of Remember the Milk's task manager wrote a script that writes a custom list of upcoming to-dos directly on a Mac desktop with GeekTool. He's sharing his script bundle for anyone who'd like to do likewise.
RTM forum user dws90 posted the script, which pulls down Atom RSS feeds from your user account, because he mostly saw other RTM-to-GeekTool scripts as "needlessly complex". His script package includes detailed instructions on how to install and use the package, and outputs fairly clean-looking, indented text—which you can modify at will, of course.
Bring your tasks to the desktop with GeekTool [Remember the Milk Blog]