Content solutions manage the most unstructured of information: web pages, email, media, and the like. Generally the source of the information is a web, email, or messaging server.
Web Portals
Sources: Web pages, media
Possible actions include content updates (e.g. comments and tags) and updates to subscription information, but you can make the portal as reactive and automated as you like.
Email and Messaging Systems
Sources: Messages, attachments, contacts, notes, calendar information
Actions are typically notifications: alerts via email, SMS, or IM. Also, the system itself could respond to alerts indicating full accounts, or abuse (e.g. spam, spoofing).
Content Management Systems (CMS)
Sources: Web content, site data (e.g. articles), embedded objects (e.g. media), version history, security (ACLs), workflow
Actions generally focus on the mechanics of the CMS, such as workflow process control (e.g. move to editorial review) or general change management (e.g. content updates, broadcasts to live deployments).