Speakers with imaging "Free of the box"

The Ohm's (in my case the Walsh 5 Mk 3) definitely do this. More importantly, they disappear as individual sources and a beautiful sound stage appears across the front of the listening room.

Duntech and Dunlavy, well built with perfect imaging.

I'm surprised no one has mentioned Alon. The Model I has stellar imaging that casts a believable soundscape. The dipole midrange mounted on an open baffle must be playing a role here. The box enclosing the 8 inch woofer is quite narrow which keeps diffractions to a aminimum.

The Totem Arro, Sttaf, and Mani-2 also deserve mention. In terms of currently available, affordable speakers, they're especially noteworthy. They disappear without much trouble.

The type of speakers and optimum set-up I am sure are important for imaging, and in my experience I tend to agree that monitor speakers and small front baffle speakers do this best. However, in my preamp search, I also found significant differences in imaging and the ability of the speakers to "disappear" depending on what preamp was being used, without changing anything else.

The Bose Acoutimass 5's did a great job of disappearing. Unfortunately there were many other reasons these were not great audiophile speakers; timbre, power handling, distortion, frequency response, transient response etc.(especially in the sub which sounded terrible)

I would definitely not pursue a speaker designed specifically for the purpose of disappearing; a balance of qualities is preferrable to having one defining feature.