Love the site--I've been trying to find a better site for tagging and organizing my news feeds (GReader can't tell the difference between a folder and a tag; Delicious requires Yahoo; etc.). I consider my $12 an investment in getting even more great visualizations and other features.
I'm writing new stuff every single day. You can track progress on GitHub: http://github.com/samuelclay. I'm finishing up Send to Email today/tomorrow, and then the iPhone app and personalization of the web interface. So stay tuned and thanks for going premium.