Mac: Trello is one of our favourite organisation tools, but one potential downside is the lack of a native desktop client. Paws jams Trello in a desktop app for Mac, complete with notifications and a handful of keyboard shortcuts. Trello has all kinds of apps for most devices, but for whatever reason, has never released a desktop version. Paws for Trello isn't much more than a wrapper for the web app, but it does integrate native notifications and keyboard shortcuts, which is enough for anyone who prefers a desktop app over a web app. That's pretty much it, but the native notifications alone are super useful with Trello. Right now, Paws for Trello is Mac-only, but a Windows version is on the way soon.
Paws for Trello ($4.49) [Mac App Store]