At Eyeo (8 developers, no two in the same place), we use:

- IRC (most of us use IRCCloud)

- Discourse (a forum, I can really recommend this even if you have chat, and Discourse is particularly good)

- Skype (only used for one on one meetings)

- Oovoo (like Skype, but has free video conferencing, we use it for meetings with more than two people)

- Rietveld (a review system, we have mandatory reviews for all changes, really really important for distributed teams IMO)

- Trello (we're in the middle of migrating to a real bug tracker (Roundup, what bugs.python.org uses) though)

- Google Drive (mostly as a wiki replacement)