In keeping with my resolution to keep the WIPs under control in 2013 (because, ahem, I'm supposed to be finishing my thesis), I have a genius new system. All WIPs go in this basket (which is about 13" square so it fits blocks in nicely). That way I can keep an eye on them, and actually notice when they are piling up. My previous system of one hundred different storage places meant I could play all kinds of mind games with myself! A simple basket. Genius.