Giant Alphanumeric Nixie Tube available for lots of $ on the 'bay
Sometimes I go to this page and just listen to the default sounds
A couple of 3-dimensional alphabets. Info on the above alphabet. The image below I came across randomly and I can't find any information about it, so let me know.
Another 3D alphabet
CNMAT's experimental spherical speaker
Interactive Acoustic Modeling from Princeton. video