We wondered last week whether there was a big enough marketplace for the new breed of quick and easy, wiki-ish document-sharing apps such as JotLive and Writely. Add another one to the list today – Writeboard, a free service from the highly regarded crew over at 37signals. They’re the folks behind Basecamp (web-based project management) and Backpack (a small business organizer). About Writeboard, which is free: “Write a business letter, copy for your website, a marketing brochure, or a product description, or a weblog post, or a song, or a poem, or an idea, or an essay, or a book chapter, or whatever else you might normally write in your email program, text editor, or word processor. Unlike a Word document that’s stored at your office on one computer, you can get to your writeboards from any computer in the world with an internet connection and a modern web browser.”