Slack is an interesting tool for those people who work on teams. It enables you to have all of your communication in one place. All of your items in Google Docs, Dropbox, and many other tools can be organized and made searchable with Slack. You can make a team, and then have categories (public or private so if you have different levels for team members you can have a category just for management). It's easy to sign up. For me, its kind of hard to bring team members into the fold (I can make it recognize an domain, so here again it is made for businesses - not podcasters). I was bmmered there is no way (that I could see after using it for 10 minutes) to make a page where people could go in an request to join my team (there is a tool for that it's call facebook). 
It turns out that Slack is from one of the co-founders of Flickr. It has been growing quickly for just being around a little over a year.
The more I play with it, the more I see its potential. I do with they had more of a "step by step" video 
If you're interested in playing with my Weekly Web Tools team, send an email to weeklywebtools@gmail.com and put the word SLACK in the subject. 
If you are looking to start your own Slack team go to weeklywebtools.com/slack