Stumbled upon two interesting links. Both search the web for images according to the hue you select. Could be very useful:
Chromatik can take not only hue but also luminosity and saturation into account, can search for several colours at the same time (you can even determine their proportion in the image), and also allows for specific word searches.
retrievr (no caps there) can search by a sketch you draw with different sized brushes and different colours, or by an uploaded image - still beta, though.
These are still not close enough to what Google's Googles is supposed to be, so I'm still searching, but interesting enough to note.