I originally wrote this program to capture the data being sent by various
programs that use undocumented network protocols in an attempt to reverse
engineer them. RealPlayer (and most other streaming media players), ICQ, and AOL
IM are good examples of this type of application.
In tinkering with it, I later also found tcpflow to be useful for checking to
see what cookies my browser was sending to various sites, looking at the MIME
headers of HTTP requests people are sending to my web server, and verifying that
various connections to my machine that were supposed to be encrypted actually
were encrypted.