I generally try to get rid of mags and keep if most of the mag has info that I want to refer to later of if its full of nice 2D girls - some of the Dengeki Hime and Megami issues are hit n miss. If there only a few pages then I will rip them out, scan or photo them and keep electronically to save space.
Been round to some comrades houses where I would see issues of mags (stacks of them) which are over ten years old ^^; What do you do with your old mags? Do you keep them in sight, stock them out of sight or trash/give them away?
