I love to walk through the reserve section of my local library...the books, records, and DVDs are lined up in the back corner, with these huge dividers, each with an oversized letter in Helvetica, organizing the reserves by the last name.
Matthew created this how-to on Flickr: unusable vinyl LPs augmented with stick-on letters slid in between physical media to keep 'em alphabetized and easy to find.
How do you organize you media and books? Genre? Author/artist? Title? Color?