Generally I buy yarn with a project in mind. I pick a pattern, then I go get the suitable yarn for it. But there are two brands of yarn that I have an addiction to, and tend to buy even if I don't have a project in mind. One is Happy-Go-Knitty, specifically the sock yarn.
My latest love though is DyeForYarn.
I first got some of this awesome yarn for my wedding shrug, and now I've just got some silk and merino DK in a really dark navy. It's almost black, and has a beautiful shimmer. The OOAK colourway is called "Black damson falls off the twig" and I plan to knit it into a really simple hat, maybe another Rikke.
What I love about their yarns is the vibrancy of the colours. I could quite happily purchase the whole store!
But before I even think about knitting a hat, I need to finish a sock. I've given myself a deadline of tomorrow. And I have no excuses left.