My current Thursday night crochet project (that's the night I watch television: Grey's Anatomy; and The Office if I start at 8pm; and Men In Trees if I finish at 11pm) is an afghan that I'm making predominantly out of recycled yarn. This is a long process because as I run out of yarn, I have to make more.
In trying to keep color aesthetics in mind, I've kept the pattern simple: fans and double-crochets on alternating rows, colors blocked by black. The black is yarn I purchased, the blue is 2/3 recycled yarn and 1/3 purchased yarn (recycled cotton thicked with a strand of baby yarn in blue).
The next color will be a dark red, a combination of yarns from two different recycled sweaters. Then back to blue again. In between each color, as you can see, is one row of black fans. I'm hoping that 75% of this afghan (at minimum) will be recycled yarn. It's very warm, and funky looking.