He asked for rock and alternative, not metal.
But if we're listing metal anyway...
Death
http://www.youtube.com/watch?v=-as4LausEok
OPETH
The Moor
http://www.youtube.com/watch?v=wpkHg8p64Yc
Demon of the Fall
http://www.youtube.com/watch?v=yrBrH5PZtcc
In The Mist She Was Standing
http://www.youtube.com/watch?v=H18p6GEaRIM
At The Gates
http://www.youtube.com/watch?v=hJme5uubkyQ
Gojira (french death metal! with protect-the-environment themes! weirdest combination ever, but I love them)
http://www.youtube.com/watch?v=f5By-5mLHk4
Isis
http://www.youtube.com/watch?v=A87P1eXFqp8
Amorphis
http://www.youtube.com/watch?v=ugUXDwBswWI
Children of Bodom
http://www.youtube.com/watch?v=d8F3t-F_grc
Kalmah
http://www.youtube.com/watch?v=mz2irxsZKH0
Mastodon
http://www.youtube.com/watch?v=v-Su1YXQYek
seen a lot of these bands live. Can't think of a bad show among them
saw Slayer Metallica and Pantera in the late 90's when I was like 14.
Metallica/Pantera fans are pretty laid back imo but some Slayer fans are fucking idiots who make it a point to try to hurt people during a show.