Project Management requires figuring out who needs to do what when. The most common method is "punch and pray" or Ready, Fire, Aim, which is exciting and all, but don't you already have enough drama in your life?
Most people use Microsoft Project for running complex projects. MS Project isn't a very good tool and it's expensive. The free version Open Source clone, LibreOffice is a lot worse. I searched for quite a while and found Rational Plan. It's cheap and it runs on Mac OS, Windows and Linux. Rational Plan for Linux is free. So, even though I run Windows on my PC at work, I can run Rational Plan in a Linux virtual machine for free.
Even though Rational Plan for Linux is very basic, for as often as I use it, it's the biggest bang for the project management buck I've found. This is far from an ideal solution, but it gets the job done.