There is Heartbeat pretty cool module with nice API. Also you can integrate with many other modules as well.

Heartbeat displays user activity on a website. This module is an API to log activity. The logged data contains message structures, attributes and variables. Once the activity messages exist in the database, they will be parsed and build into activity streams.

Other modules that work great with heartbeat activity

Facebook-style Statuses

Flag

flag friend

Friendlist

User relationships

Display suite

There is Heartbeat pretty cool module with nice API. Also you can integrate with many other modules as well.

Heartbeat displays user activity on a website. This module is an API to log activity. The logged data contains message structures, attributes and variables. Once the activity messages exist in the database, they will be parsed and build into activity streams.

Other modules that work great with heartbeat activity

1. Facebook-style Statuses
2. Flag
3. friend
4. Friendlist
5. User relationships
6. Display suite