http://stackoverflow.com/questions/1...ernet-in-linux mentions netstat, lsof, nethog and watch and also few examples on how to use them best.
Found this using Google with these search terms:
display programs using internet linux -windows -max -ios -w7
A lot of times it's not so much about using a search engine but rather about using it right, so it filters out all the garbage. (That's what the "-" does.)