When you work with distributed teams it is important to have lightweight tools for efficient communication. Here are some free tools that I would recommend:
Surveymonkey – Online polls
DFN Scheduler – Scheduling
Skype – Video and voice conferencing
Chatzy – Private web based chatrooms (port 80 only, mobile access)
Trello – Scrum and Kanban boards (highly interactive)
Kunagi – Scrum boards (includes tools like planning poker)
Teamviewer – Online meetings and remote control (free for non commercial use only)