theres a lot of factors that can involved, you got proxies, name servers, IM., email, realaudio, win amp.
it would help to know what os your using and how its configured.
Is it a server, workstation, *nix, win9x, 2k they'll all give you a different netstat printout.
isa listens on every port.
it all dependes whats running on your computer, if you get a firewall it will usually name the processes trying to access the internet. Theres also a program called Fport that gives you a read out like netstat and names the processes that are listening.
