The Columbia Journalism Review (CJR) has been tracking online news operations for a while, and a year or so ago, started compiling them into a database, which I had listed in the resource links to the right. At some point, they renamed and restructured the site, and gave it a new URL. It's now called CJR's Guide to Online News Start-ups - I've corrected the name and URL on my resource list to reflect the change.
The list is by no means complete - it still doesn't have our own TNJN.com or several other Tennessee online news sites I'm aware of. But it still is a searchable resource that provides information on a growing number of online news start-ups.