Sometimes yarn isn't all about knitting fun. Sometimes you have trouble finding exactly what you want, so you have to pull out all of the yarn you own and put it in the middle of your living room.
Okay, so this is no longer a hypothetical 'you' and more of an I did this. The yarn left over from my blanket is in the lower right, the larger clear container on the left has some acrylics I've picked up on sale, one of the smaller clear boxes is empty and the other has some sock yarn I bought at the same time as the smaller containers. They're airtight, so I decided to fill them with wool.
I have no gone through everything in my stash and put it on Ravelry so I can see exactly what I have and how much I have. If I find a project I want to make with a specific yarn, I put that in my queue immediately so I won't forget (though I might end up changing my mind). ALL of the yarn is now in one of the plastic bins, in one specific storage cabinet (the things I got in a full bag sale and a few cones of cotton), and my blanket leftovers have all been kept together in a box. I don't know why, but I really like that they're all together.
This organization has reminded me I have some beautiful yarns. Now, what should I do with 5 same dyelot skeins of self striping sock yarn?