Here is a new theme for Moodle 1.5.2, 1.6-dev. It's called GINAqua and is based on Moodle's standard theme.
One of the professors in my college complained that the headers and the sideblocks occupy a substantial part of the workspace. So, a "display/hide header and sideblocks" button is available at the top right (only for the logged in users). You can also use the shortcuts Alt + 0 and Alt + 1 to display and hide the header and the sideblocks. The button can be disabled by commenting few lines in the header.html file (search for comment these lines to disable the "display/hide Header" button).
I also have a question: Is there a way of incorporating Print Preview (media="print") and alternative stylesheet in Moodle 1.5 themes?