We have been using tinyPM as our main tool to coordinate our work on www.susuh.de for more than one and a half year by now–and we neither could nor want to do without it. :) As we are working in distributed locations (Berlin and Wroclaw) and using the agile development methodology at the same time, most of our work project-wise is based on tinyPM. I particularly like the possibility to set up new user-stories for discussion and estimation so easily.