Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
openDesktop.org - The website openDesktop.
Wiplo - The easiest way to organize and run your business workflows.
SourceForge - The Complete Open-Source and Business Software Platform.
Toby for Teams - Better bookmarks, now with collaboration baked in 🔖
Freecode - Freecode (formerly known as Freshmeat) is one of the legit open source development platforms that will be the key for developers and programmers to have a streamlined process via having enhanced collaboration and coding leverages.