The fact of Interpid Beta having so awful system sounds and a weak wallpaper made me having an idea:
What about having a sponsored competition for each Ubuntu version artwork, like wallpapers, system sounds, gnomecc/kcsrc colour schemes, themes, etc.?
The prizes would be sponsored, symbolically (like Ubuntu merchandise, more shipit install CDs, etc.) or not (like computers with Ubuntu OEM), and i think this not only will not hurt artwork licences like cc-nc-sa or gpl, as well this can provide Ubuntu plenty of much better artwork (specially from the artwork .deb packages each version, having hundreds of excellent artwork instead of some few mediocre (poor) ones), and help increasing the Ubuntu popularity.