EDD Blog Ride the Lightning points out that the copy machine is a favorite, and usually overlooked, source of data:
Most of the law firms we see haven’t a clue that their digital copier (typically configured as a network printer too) may contain recoverable data. The majority of currently available digital copiers contain a hard drive. It is prudent to buy or lease a digital copier that can perform a secure wipe, thereby ensuring confidentiality. Our own copier is set to do a secure wipe after each job, probably a good practice for most lawyers to implement.
Probably a good practice for most businesses to implement, too.
They also link to a funny advertisement featuring a photocopier and an office worker discovered in, shall we say, a compromising position. Good stuff.