We use Pivotal Tracker, Skype group chat, TeamViewer, Dropbox, and email. I'm pretty happy with this setup for daily/weekly product development and planning. I do want to give Trello a try though, to keep track of hi-level tasks (e.g. doing research) and on-going brainstorms (e.g. strategic product decisions) that are not immediately tactical/dev tasks. Would love to hear thoughts from people who use Trello or other tools for these purposes.