Glassboard is a neat cross platform (iOS, Android, Web) app that helps people to communicate within teams while on the move.
You download the app – or use the web version – and create a ‘board’ which is where you post messages and files. Then you invite people to join that board, and only they and you have access to what is posted there.
Even better, you can choose to have people join by using an invite code rather than receiving a specific invite. This means that, for example, you could create a board for all the members of an email newsletter to join to be able to chat. Just include the invite code in the email, and all those who you want to have access can do so.
It works really nicely on smartphones – the web interface is a bit clunky, but then, it’s made for mobile I think. It also is a nice, more lightweight alternative to a Yammer network, which can sometimes feel like taking a sledgehammer to a nut, I find, when all you want to do is have a quick chat now and again with a group.
Glassboard is free for 3 boards. For unlimited boards and a few other features, you can go premium for a very reasonable $5 per month.