Ditto fermunky's comment - IMHO the current themes waste a fair bit of screen space with big chunky icons (like the bookmarks icon for example) - I'd like to see (or be able to make myself!) some 'lite' ones and or some funky mac or firefox inspired themes

The current themes are only really colour variations of one theme... (I like the red ones best - the blue ones look very 'grey' - if that makes sense!) hopefully soon we'll see a maemo/'Internet Tablet 2005' section on http://themes.freshmeat.net/