My previous system was apple boxes from the grocery store where I work. Anyone with experience with apple boxes knows that these are among the premier boxes you can hope to obtain when getting boxes from the grocery store (egg boxes are pretty good too, in case you were wondering, or planning to move sometime, ask specifically for apple boxes and egg boxes, trust me on this one). However, I just tossed yarn in the boxes and forgot about it, which made it extremely unlikely that it would ever get used.
While at the in-laws, I came across several of the big, plastic things that sheets, and other bedding comes in. You know, they are like boxes, but made out of plastic and with zippers. The in-laws had recently purchased some new bedding for the rental villa that they own, and had four of those. I added that to the one I had from a recently purchased mattress pad.
After stashing the yarns that had already been assigned projects, I sorted the rest by weight, making separate piles for worsted, sport, dk, fingering (non-sock), and lace yarns. Each was placed in one of the bags, and labeled with the weight of the yarn.
It works pretty well, the bags are clear, so I can see what is inside of each one, and they are stackable for easy storage.
However, the yarn was not nearly as safe as I had hoped. Someone already managed to chew a hole in the side of the lace weight yarn (and of course, the lace weight, the easiest to tangle and biggest pain to untangle). But since these bags should be stacked in the closet, with the door shut, this should not be a huge problem. I'll patch the hole with some packing tape, and see how that goes.
This project brought about another boon too. While digging through the yarn boxes, I discovered a stash of worsted weight golden brown yarn that will be prefect for a project that I'm planning. (and yes, for those who are wondering, that is Vanna White on the yarn labels, she's an avid crocheter and has her own line of yarns through Lion Brand).

I'm making an afghan for one of my oldest friends as a wedding gift. I want to make the Yggdrasil Blanket, by Lisa Jacobs. It is a wonderfully complex pattern with lots of cabling (which most likely makes poor husband shudder when remembering the string of profanities that came out of my mouth the last time I made a cabled afghan). The tree motif reminds me of this particular friend, who is very outdoorsy.

As luck would have it, the yarn is very close to the color that I was planning on buying for this project. And, it is an acrylic yarn, which personally, I'm not overly fond of (I prefer natural fibers), but acrylic is durable and machine washable, two things which make it great for this particular friend, who bless her heart, I cannot imagine that girl hand-washing a blanket. The wedding isn't until the end of October, but I want to get started right away so I can work on it at my leisure, in between other projects.