I've been a solar enthusiast since I was a kid. Photovoltaics historically were expensive and a little out of reach for experimentation.  How times have changed!

Here's another: solar cells from blueberry juice:

http://chem.pdx.edu/~wamserc/Research/JCE-Gratzel.pdf

With the current economic system turned upside down, big, amazing things are on the way. These sorts of ideas and opportunities are going to have space to flourish. There was no space for this sort of thing before, what with entrenched interests and all, but now... It's going to be awesome!

Update: Los Alamos National Labs has demonstrated the transfer of excess energy to neighbouring atoms in a crystalline lattice via phonons. This discovery raises the potential efficiency of solar cells to 40%.