I'm bootstrapping a Disqus "clone" that I plan to open source and offer hosted versions as a SaaS company.

I'm still building the MVP but I have a demo running here: http://www.remarkbox.com

I've taken special care to not hash user emails when generating avatars.

In addition by default:

* users are anonymous

* Gravatar is disabled

For default avatars I plan to fork https://github.com/Bekt/invatar (to add image caching)