Good for you on expanding your musical tastes.
First if you like you can start off with
[B]http://www.music-map.com/[/B]. How that works is you type in a band/artist you like and according to that it finds other bands and artists similar to yours and arranges them on the screen like a mind map. Very cool.
Have a band picked that looks interesting but can't decide whether you like them/haven't heard anything by them? Try
[B]http://www.seeqpod.com/[/B] (originally posted by Switch) or
[B]http://www.musgle.com/[/B]. Seeqpod works by typing in the band name and clicking search, where it finds mp3's online for you to stream. I think there's a way you can download them, but I haven't figured out how/never really bothered. Musgle works exactly like Google. Type in a band name, and it finds mp3's of them you can listen to online/download. Pretty handy.
Finally if you have that song stuck in your head, but can't remember the name try
[B]http://findmeatune.com/[/B]. Just type in any song lyrics you remember and it should give you a name. It hasn't been very reliable for me, but some of you might have better luck.
I hope this helps, if any of you have any other suggestions, post them up. I'll edit them into this post. A mod might even sticky it?
Last.FM. Works kind of like a radio station. Type in a band you like and it finds similar artists on certain stations for you to listen to. If you want to use it you need to sign up and download the software, but it doesn't take that long. Thanks Aoife.
Pandora.com. Like Last.FM only it will not work for you if you are outside of the United States. Thanks Tempest.
Allmusic.com for information etc. Thanks Twiggz.
Owlmusicsearch.com helps you to literally find music that sounds like yours. Thanks Tempest.
Songtapper.com works the same as FindMeATune. Thanks Gizza.
PureVolume.com hosts a load of signed and unsigned bands for you to listen to. Thanks Beermonster.
Sectionz.com to listen and download free electronic songs. Beatport.com acts more like a directory for finding electronic artists, downloads are not free. Thanks Exetra.
ProjectPlaylist.com is the same thing as Seeqpod. Thanks Matt.
Songza.com works the same way as Project Playlist and Seeqpod do and it can find covers, live tracks etc.
Wiki. Look up your favourite bands and artists and see who they are connected to and what bands are similar/in the same genre. Thanks Raxo.
Imeem.com Used for streaming and downloading mp3s, but you need to make an account. Making one is very simple though.
Midomi.com Find songs you are looking for by humming the melody or singing the lyrics into a microphone. Works very well. Thanks Chocoholic.
Did it leak.com Find out when albums have been leaked. I check this site almost daily and it has been very handy for me. Thanks Tweek.
Musicovery.com A visual radio station where you can pick genres, years and even the moods of the songs. Pretty nifty. Thanks BlackKohm.
Mog.com Like Last.FM but has a really great user community and can be used for discussing music as well as listening to it. Thanks Tunacake.
Metal archives.com The name pretty much explains it. It's an archive of metal. Thanks The Omnipotent I Can't Read The Rest Of Your Name.
Live plasma.com It's a lot like music map and you can search for movies as well as music.
Filter music.net A list of internet radio stations that specialise in a plethora of different genres.