John Stockdale of Paignton, Devon, proposes a wine exchange, where rare and ordinary wines would be auctioned and tasted. Jonathan Trapman, of London E8, suggests a meditation centre for City folk to exchange self-interest for compassion, kindness and honesty.
There were lots of suggestions for museums - of the decline of the British merchant navy, of building materials, of financial markets, and of modern art, among others.
But the bottle of bubbly goes to Deborah Jefferies, of London N16, who proposes 'a fantastic baths and steam rooms, similar to something you might find in Budapest as in the Gellert Baths'.
The pictures of the two interiors show the Baltic has great potential as a giant turkish bath. It would be a wonderful place for City financiers to meet face to face and negotiate deals without the distracting trappings of screens and suits. It's hard to be dishonest with no clothes on, I'm told.
Alas, Nicholas Baucher, of Hillier Parker, the agent handling the sale of the site, is dubious. 'The hall is 500,000 cubic feet,' he tells me. 'That's an awful lot of steam.'