Ashen Shugar: Tool is pretty brilliant. A mix of metal, psychedelia and prog. The best albums to start with are either Undertow, their debut, or better yet the last album, Lateralus, simply one of the best albums I've ever had. A Perfect Circle is Tool singer Maynard James Keenan's side project - a bit less heavy than Tool, more melodic on the whole and more 'personal' in feel. Mer du Noms is their debut, and a great album. The follow-up, Thirteenth Step, comes pretty close and they've just released an album of anti-war songs which I've only just heard once so far.
Now listening to The Darker Days of Me & Him by PJ Harvey.
