First off I don't use itunes for what it was intended to be used for, which is makeing money by charging a dollar a song. It is a great way to store and manage music that is already downloaded on you computer already, but it is a great way to hear samples of songs.
This section on the main page of the itunes store is continuously updated and is a very easy way to see what new albums come out everyday
While it is a good idea I find it kind of a waste of time. The idea behind this application is to look at songs already downloaded in your itunes and give u a list of songs that are like what you have. What it ends up giving you is a list of songs from artists that you already know.
Itunes essentials is the most usefull application on itunes. I have used it as a doorway into eras and genres of music that i have not yet explored. It contains many 100 song playlists from every genre and era of music. ITunes does a good job of makeing these playlists very accesible, but usually very mainstream. It can be found by searching for itunes essentials and then clicking on itunes essentials in the bottom righthand corner