TFS has several extremely useful service hooks available out of the box, including the following integrations (descriptions taken from TFS):
Azure Service Bus: Microsoft Azure Service Bus provides a hosted, secure, and widely available infrastructure for widespread communication, large-scale event distribution, naming, and service publishing.
Azure Storage: Microsoft Azure Storage is a service for storing large numbers of messages that can be accessed from anywhere in the world. It is useful for creating a backlog of work to process.
Bamboo: Bamboo is a continuous integration server from Atlassian.
Campfire: Campfire provides team collaboration with real-time chat. It is like instant messaging but is designed exclusively for groups.
Flowdock: Flowdock provides chat and inbox for teams, providing one place to talk and stay up to date.
HipChat: HipChat, from Atlassian, provides group chat and video chat built for teams.