I'm currently in a hat kick currently. It started when I was working on my BIL's trilobyte hat for his birthday.
It turned out lovely and the walnut Cascade Superwash 220 knitted up soft & lovely
However, I had some left over from the skein when I finished it, so I decided to cast-on another hat (Turn a Square) and supplementing it with the Yak I had spun up previously
The colors were in approximately the same brown shades/tones, and looked really well together. At first I wasn't sure, but the walnut of the Cascade muted the dark brown of the yak.
I managed to finish the hat in a single day; I couldn't stop knitting.
DH tried it on, and although he's not normally a hat person, it goes really well with his coloring, and he claimed it for himself (esp. as the trilobyte was already claimed).
So, guess what I did after I finished this hat? Dove into the Stash, pulled out some more Cascade 220 superwash (along with leftover yarn) and cast on another hat.