Hot answers tagged newsgroups
Do you know the Open-News-Network? They have Webnewsreaders. Not sure if it's what you're looking for.
Check out http://www.ccparcel.com/ if you're still looking :)
I believe that Yahoo Groups should do everything that you want. I have run private groups with multiple moderators, and users can add or remove themselves as they see fit.
I know that Marc Smith did research into analyzing and visualizing newsgroup activity while he was at Microsoft Research. I don't think it was a webapp, but it was called "Newsgroup Clouds". I have no idea how he gathered the data for analysis -- if he was subscribing to the feeds over time, or if he could analyze a new newsgroup on demand.
Only top voted, non community-wiki answers of a minimum length are eligible