I have old Lundia shelves for CDs, LPs and irregular sized objects. also have a separate Lundia for books. Lundia is a Finnish company who make quite boring looking but very adjustable / expandable and durable shelves, think Ikea's Billy except better quality wood etc. being used. it's very expensive new, but roaming the second hand places pays off.
however, I haven't found a suitable way to store / display normal tapes. I currently have them in random boxes and piles, which is a drag since every time I get something new it gets a couple of listens and then just disappears into the heap of obscurity. every time I see a decent tape shelf at a friends place or where ever it's usually a lucky find from a recycling centre or something like that... suggestions??