If I look around this beautiful and inspiring thread I notice that most people with large collections sort their Lego by colour and subsequently by the various different and special parts. At the moment I don't have room for anything elaborate (I'm still waiting to find proper housing -- here in the Netherlands the housing situation is FUBAR), so I just use ziplock bags to store sets as I purchase, build and dismantle them, and store those in flat, stretched containers that roll under my bed and various other places.
My cupboards also overflow with ziplock bags :)
But my question here is how do you feel about sorting as described above, versus sorting by set or theme? Say that everything gets mixed by colour, isn't it a hassle then when you want to rebuild a particular set? Considering the prevalence of the former system with larger collection, I assume it is the more robust option. But part of me rebels against breaking up and spreading all the various sets I have into nondescript piles of Lego.