It seems like there are many niche markets that do not yet have a sophisticated online marketplace developed for them.<p>For example, it was only recently that Flippa.com emerged (from SitePoint marketplace) as a marketplace catered specifically to the needs of website buyers and sellers.<p>My question for HNers is this: What markets are in the greatest need of a new, sophisticated marketplace?<p>Some examples I have considered:<p>- coin and stamp collecting<p>- artisanal foods (e.g. cheeses)<p>- baby products<p>Thanks!