I'm fortunate enough to have a loft. Boxes go in there for 1-2 years, depending on the item, then get recycled. If short of space, I fold up (but not really useful if they have those polystyrene inserts)
I also use the space to save all sorts of boxes and packaging. It used to get commandeered by odd family members who were moving. Recently, as they've settled more, I tear off any labels that identify me as I put it away and save until I have a couple of large boxes / bags stuffed with packaging, then put it on Freecycle. People who are moving, small businesses, ebayers etc. use it, so helps save from landfill.