One of my favorite teacher tools is the file/milk crate.
Milk Mate Mailboxes
I use expanding hanging folders for each class period and file folders with each student's name. This is how I return papers to students and I even place handouts in their "mailbox" if they are absent so they can collect all their work with they return.
Another idea I'm working on I got from http://whattheteacherwants.blogspot.com/2011/07/i-gave-in.html. A crate seat.
Place the crate on it's side and use it to hold classroom books.
Use a crate to store a class set of iPads and easily take them where you are working.
Secure a white board to the top of the crate and use it as a writing desk.