We've been using slack for new projects at work lately. We used Skype in the past and still do for calls, screen sharing and one-on-one chats but slack channels are a far better fit for team chats and keeping track of conversations related to a specific projects.
A Chrome extension that removes pesky trip to slack-redir.net when clicking on links in slack.
Get slack-direct at the Chrome Web Store. Checkout the source code on GitHub.