[oniTony]

Most social networks are in various shades of blue. http://www.quora.com/Why-are-most-social-networking-sites-bl...

[michaelchisari]

I'll concur with this. Originally, Appleseed was green, and people hated it. I tried various different color schemes, and while I don't think social software has to be blue, blue color schemes are definitely the easiest to make work.