I've been on a music mission for years now.  For some reason, the tops 40's usually don't do it for me.  My favorite artist is Tori Amos.  I have seen her in concert twice and she has such a gorgeous voice.  But, I wanted to find more artists like her and I did!  I have found them through a few different methods and you can do this too with your favorite artists.  I joined a forum for Tori and there is a thread about other favorite artists on there so that's where I learned about Charlotte Martin, Imogen Heap, and more.  I've also learned of new artists through www.Pandora.com.  Do you know about it?  It's awesome.  You plug in your favorite artist and they play like artists.  A little card comes up with the name of the song, artist and album and you can click on any of the three and find out information about them and even what other people who like your artist listen to.  It's full of great stuff.  Try it if you haven't.  I also go to MySpace music.  You don't even have to have an account.  You can explore artists that way.  You're not going to hear them on the radio or find them in the store, for the most part so if you are bored with the top 40's like I was, these are some ways to discover new music, right from your home.  One other way that I just found out about (call me slow) is iTunes.  If you download their music store, you can listen to parts of songs to see if you want to buy them.  It's great!  

Good luck!

Some other artists that I found are:

redboy
Iris Leu
Andy Laird
Christopher Jak
Sara Shansky
Sia (a friend told me about her)
Anousheh Khalill
Leroy Bell
Killarney Star

P.S.  I also like Linkin' Park and Eminem, along with all kinds of other stuff.

Sounds cool, will try to hear them all atleast once.

That sounds good, I'll try to listen to them.