IKEA Expedit closet - It's just a simple 2x2 Expedit unit without the inner shelves but with the addition of a closet rod. The 2x2 sits on a 2x8 Expedit, which saves on floor space. Check out IKEA Hackers for a detailed shot of this closet.
Puzzle storage!! Best way to store kids puzzles! Buy some Legal size poly expandable envelopes. Remove the string and replace with Velcro circles. Place in a bin or on a shelf. My rule is one out at a time. The envelopes are easy enough for my two year old to open and clean up himself.