One of my 2015 projects is to complete a sky scarf. Each day I knit a row in the color of the sky, wherever I am. This makes a somewhat-tonal seed stitch scarf, and an interesting diary of the weather for the year.
It is Knit Picks yarn, which is my favorite budget friendly knitting source. I'm using their Palette yarn, which is named for its expansive range of colors and is designed for color work.
It is already interesting to look at it and remember some of the big winter storms or especially snowy days. (Notably, the first couple rows of dark gray at the beginning of January when I was in the hospital giving birth to my son.)