One word...piecework. Seriously, there is nothing less appealing than having a large project (even cotton) piled up on your lap. This summer I began making squares for this.
This may very well be one of those projects that takes years to finish, bit by bit...but it's so easy to toss the project bag in my laptop case and go. This wil be especially awesome when I start taking the commuter bus next month... more on that later.
Oh, and Koigu... I finally get you.
While this can certainly be knit out of any sock yarn, I am knitting this out of both Koigu and Malabrigo Sock, as they both have the same hand.
Another way to keep my hands working with yarn is weaving... nothing to pile on your lap! I did have to move the loom inside since the studio is simply an oven these days.