What kind of information goes out of a corporate network to the world?

I'm trying to do some self study on security and networking integration and it occurred to me. In an environment where you run, say a Bluecoat ProxySG, that intercepts all web traffic. But what other traffic would go out an external gateway (that may required ASG services on a firewall)?

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I can think of VPN and encrypted tunnels for data transfer/replication. FTP maybe if that's not counted as regular web traffic through a proxy.Streaming services and conference/telephony connections. Is there anything else I'm just not thinking of?

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I know SAN replications stay internal, they'd never (or very rarely) go out to the world.