While they may seem meaningless, hey are essential space-fillers of awkward pauses and indicators of the speaker's attitude.
Interjections are also the first and easiest words to learn in another language.
This is all the more true for learning Japanese through anime. Others are not so easy - see below for a rough idea of their translations. Just a minute. Page accessed times, column accessed times since October 16, 2000. Rodney Romasanta for Cal-Animage Alpha.