HuluPlus is good for carrying currently running content and acts like a DVR. They carry a good deal of content from Fox (broadcast), ABC, NBC and some other networks I like including Comedy Central and a few others. CBS is not represented at all really.
Netflix and Amazon Prime have a good deal of the same content but sometimes Netflix has a TV series free whereas you have to pay for it on Amazon.
Redbox Instant, Target Instant also seem to carry the same movie content as Netflix and Amazon.
Netflix's main advantage is simply that they carry more content however the quality of the excess stuff is surely questionable.
I am hooked on foreign programs with subtitles still.
Love Dramafever.com and Viki.com