Collaborative Software

Software for collaborative work

VoIP

 * Skype
 * Mumble - Open Source, Press-To-Talk, Android

Screen Sharing

 * TeamViewer - free

File Exchange

 * Dropbox
 * SparkleShare - p2p, open source, servers can be added, unlimited GBs.

Document Writing

 * Google Docs
 * Etherpad - Open Source
 * Sync.in

Project Management

 * Scrumy
 * Trello