Cost: Free for 12 users and up to 5GB of online storage. Premium plans start at $99/month, supporting unlimited users, additional features, and 50GB of online storage.
Available on Android too? Yes
Bitrix24 is a cloud-based collaboration workspace that lets business users create a "social intranet" that helps workers collaborate on the many aspects of daily operations and tasks. It features an activity stream, video chat, "like" buttons so you can approve of various things coworkers have accomplished, and layered security. The mobile app allows you to manage all of this from your smartphone.