We mentioned one form of Tetris shelves from New York's Brave Space Design a few years ago; but there are several options you may have missed if you saw these beauties way back when. While the regular open work shelves don't have a price listed ('Contact us for a quote!' is rarely a good sign for your wallet), you can get the colourful "flat" set for a mere $US 1500 per 10 blocks or the lovely bamboo version for $US 2000 per 10 blocks. Despite the expense and the fact that Tetris-inspired bookshelves would clash horribly with my decor, I think my books would look fabulous nestled in these creative, if pricey, shelving units.
Tetrad Shelving [Brave Space Design]