Nice idea!
Well, Brazil has a lot of genres and a lot of artists that should be mentioned, but let's start with rock. I'll post other genre later.
ROCK
Raul Seixas - the first brazilian rocker
http://www.youtube.com/watch?v=U0IXq1x1wcU
http://www.youtube.com/watch?v=Rxo9o-Twz3I
http://www.youtube.com/watch?v=vD_qEj-AIsY
http://www.youtube.com/watch?v=MqQq_ykY_j0
http://www.youtube.com/watch?v=cn0S56WPkjQ
http://www.youtube.com/view_play_list?p=54F57B7AA3923ABC&search_query=raul+seixas
Os Mutantes - 60s psycodelic rock
http://www.youtube.com/watch?v=5ohTi8lbeok
http://www.youtube.com/watch?v=g2EKghlmIyQ
Secos e Molhados - can't say they're a rock band, but people say they were the inspiration to Kiss look, so... Great artists nevertheless
http://www.youtube.com/watch?v=wIyvM9Ce7mM
http://www.youtube.com/watch?v=7nEf7qDskUc
http://www.youtube.com/watch?v=mrJgYwIlG0Y
http://www.youtube.com/watch?v=t63MPf1daCA
Casa das Máquinas - known as the brazilian Led Zeppelin
http://www.youtube.com/watch?v=pfXeRkkBXlc
http://www.youtube.com/watch?v=2Tk3MIlK9Ps
http://www.youtube.com/watch?v=mvGb45IIvkk
http://www.youtube.com/view_play_list?p=E337689038C2E5E0&playnext=1&playnext_from=PL
Cazuza - an influential rock artist
http://www.youtube.com/watch?v=AuZ6ubVXOoo
http://www.youtube.com/watch?v=jSXMHJLVdGk
http://www.youtube.com/watch?v=u-xItSZrxIs
http://www.youtube.com/watch?v=mIGhPJG9cR4
http://www.youtube.com/watch?v=NkNv2BflaSU
Blitz - a theatre group that turned into a band, very original music
http://www.youtube.com/watch?v=fYnYtT88mCI
http://www.youtube.com/watch?v=MCXcIv3il1k
http://www.youtube.com/watch?v=ydCwzcKSKMc
http://www.youtube.com/watch?v=R7Sy-Ywb6XY
Titãs - a 80s rock band
http://www.youtube.com/watch?v=kbykw7Dv3j8
http://www.youtube.com/watch?v=X-4cQAjhjBU
http://www.youtube.com/view_play_list?p=3C257465CF8AB600&playnext=1&playnext_from=PL&v=lh-G0zV39Io
http://www.youtube.com/view_play_list?p=3C257465CF8AB600&playnext=1&playnext_from=PL&v=Mr6AsUEOAvg
http://www.youtube.com/view_play_list?p=3C257465CF8AB600&playnext=1&playnext_from=PL&v=8sR8lb7xnkk
http://www.youtube.com/watch?v=HlgdZ4lYIyE
http://www.youtube.com/watch?v=H_U_JNHEUrI
http://www.youtube.com/watch?v=mVhJQLbhvfE
www.titas.net/
Paralamas do Sucesso - some ska-rock
http://www.youtube.com/watch?v=sxBPKpwb7yI
http://www.youtube.com/watch?v=cfi9K97ulmE
http://www.youtube.com/watch?v=4UPK8TU8sAM
http://www.youtube.com/watch?v=M2ijt9sg-pQ
http://www.youtube.com/watch?v=n7OZBeVfgbs
osparalamas.uol.com.br/
Legião Urbana - another important 80s rock band, remind me The Smiths sometimes...
http://www.youtube.com/watch?v=059HEaYRve0
http://www.youtube.com/watch?v=KjQ2k1hU5aQ
http://www.youtube.com/watch?v=PKvCQdF2QY8
http://www.youtube.com/watch?v=eL6zdEwRKws
http://www.youtube.com/watch?v=nM_gEzvhsM0
Inocentes - 80s punk rock
http://www.myspace.com/inocentes
Cólera - 80s punk rock
http://www.myspace.com/brazilpunkcolera
Ratos de Porão - Hardcore
http://www.myspace.com/ratos
Mukeka di Rato - grindcore
http://www.myspace.com/mukekadirato
Raimundos - punk rock/hardcore
http://www.youtube.com/watch?v=TQ7V5tbX-DM
http://www.youtube.com/view_play_list?p=7E5F6DF167A40018&playnext=1&playnext_from=PL&v=Nhjy5-w8poo
http://www.youtube.com/watch?v=7WGnoRKRGLY
http://www.youtube.com/watch?v=dW3_feB5bPY
http://www.youtube.com/watch?v=VG13C6NC8tA
http://www.youtube.com/watch?v=0e6XfnSLIWQ
http://www.myspace.com/raimundos
Nação Zumbi - mangue beat/maracatu
http://www.youtube.com/watch?v=ICHvZwueL_Q
http://www.youtube.com/watch?v=UslyiGASz7k
http://www.youtube.com/watch?v=mkNgOaF-y6U
http://www.youtube.com/watch?v=kYH82BdpRfw
http://www.youtube.com/watch?v=90HmcQmMviQ
http://www.myspace.com/nacaozumbi
Planet Hemp - rock and hip hop mix
http://www.youtube.com/watch?v=s__6WYKhTNk
http://www.youtube.com/watch?v=JD0FidNLI6g
http://www.youtube.com/watch?v=dwoohGu-NXg
http://www.youtube.com/watch?v=T5Z4I2RHSeI
http://www.youtube.com/watch?v=5ghdduDbFIQ
Matanza - just rock
http://www.myspace.com/matanzacountrycore
MQN - garage rock or something like that
http://www.myspace.com/mqn
Maldita - reminds me Marilyn Manson
http://www.myspace.com/bandamaldita
Móveis Coloniais de Acaju - I don't know what to say, just listen...
http://www.myspace.com/moveis
Margot - some indie stuff
http://www.myspace.com/bandamargot
Macaco Bong - instrumental rock
http://www.myspace.com/macacobong
Angra - heavy metal, some of you may know it already
http://www.myspace.com/angraofficial
Sepultura - trash/death metal
http://www.myspace.com/sepultura
Tuatha de Danann - folk/celtic metal
http://www.myspace.com/tuathadedanann
Massacration - some guys making fun on metal bands
http://www.myspace.com/massacrationofficial
I may have forgotten a lot of people but that's it for now.