There is not many open source project management tool has the very nice UI like this tool! We have tried to use it in our company, and we are very pleased so far. Thank you.
I did use several open source tools to manage the projects in our organization, name of few are Redmine, libreplan or agilefant. MyCollab is simply the best, it has rich features, clean UI and stable. Hai and team also kindly support us nearly instantly via email.