Eavesdrop is a network tool which lets you watch TCP connections and record the conversation. I find it useful for watching what kind of information certain programs are sending/receiving for the purposes of duplicating that conversation with another program. I did something like this in my post about BitTorrent info scraping, only not with Eavesdrop, as the program I was watching is a Windows application. It’s quite handy if you’re curious what’s going on between your applications and the rest of the internet.