If you're not familiar with Microsoft Lync, don't feel bad - I had no idea what it was before today, either. Makes sense, because I don't work in an environment where Lync is used (or would be useful), but for those who do, it's actually pretty cool. In a nutshell, it's an IM/contact management/VoIP client used for Exchange - think MSN Messenger with a GTalk twist built for the corporate environment .
The Android version allows you to see your colleagues' availability on-the-go, as well as initiation an instant message, email, or phone call directly from the app. You can also connect to Lync conference calls quickly and easily - no passcodes or conference numbers required.