Some software just fits in. This was the case with Trello and has happened again last week when we found about Slack for the first time. At Zemanta, we have used Internet Relay Chat (IRC) since ever to communicate internally in the engineering organization. But due to its geekiness IRC never quite caught on with our colleagues on the other side of Atlantic. Our more business-minded coworkers have experimented a bit with Yammer, but this privatized version of Twitter never gained any tracking, and it's too limited in its options anyway to be useful for communications between engineers. Slack is IRC that doesn't suck. It keeps the simple mental model of a chat with channels and streams of messages, but fixes many little details that frustrate users of IRC such as editing past messages, simple exchange of files, snippets, and links, full archives of past conversations, and many more. All the extensions and fixes that Slack provide come without loosing the full power of IRC, since Slack supports integrations with several services (e.g. Trello, Twitter, GitHub) out of the box and enables one to write bots on his or her own. It took just one icy Friday night to adapt our favorite IRC bot Breda the Tree thus making Slack as homey place to hangout as our old IRC was.