Quite a few options in the $150 range.
I'm just re-iterating what people have been suggesting for me, but:
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For primarily gaming, and pretty much gaming only, go for AD700s or HD555s.
Both will disappoint a bit in the music and movies side, because although they are accurate, they are both a bit bass light. Now, that doesn't mean the bass isn't there, it just means that it lacks the punch or rumble of, say, a Skullcandy headphone (YUCK). However, if you are highly competitive in gaming, the AD700s and HD555s are great for it, large soundstage, light bass, and accurate positioning make hearing footsteps a cinch.
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For music, get whatever Grados were suggested (I don't know anything about Grados, just that they're great for rock), SRH440s, ATH-M50s, or HA-RX900s
modded.
I personally own the RX900s, and I've got to say, after modding it, I was amazed by how great they sounded. Some audiophiles say that the RX900 modded is actually better than most headphones in the sub $150-200 range. I'm not so sure about the RX900s performance in metal, but its all around great for music. gaming (the RX900 has a very large soundstage, and I was able to pinpoint footsteps very well in CS:S) and movies from my experience.
If you need a less bassy experience, the RX700 is reported to be just as good, if not better, than the RX900 in terms of balance, value, and sound.
Have a good time picking!