Stuff... Guitar, Primal let-loosery, Philosophy, Music, Anime (.hack, Trinity Blood, Samurai Champloo, Eureka Seven, Bo-bobo-bo-bobobo), sacred alliances with benevolently sentient alien warriors ... etcetera ...
Lots...
Wintersun/MorsPrincipiumEst/SpawnofPossession/IntestineBaalism/Nasum/Windir/Myrkgrav/Falkenbach/JasonBecker/InBattle/MartyFriedman/Outworld/DarkFortress/OmniumGatherum/JohnWilliams/Kalmah/Norther/(early)Destruction/Witchaven/NocturnalBreed/Angra/VisceralBleeding/Edenbridge/RevoltingCocks/Ensiferum/TangerineDream/AuroraBorealis/Nile/Forefather/Coroner/Eluveitie/Razor/QuoVadis/Arsis/Deathchain/Golem/Lykathe/NeguraBunget/MeadsofAsphodel/HeolTelwen/Haydamaky/GammaRay/Gorath/TheFirstborn/Taake/Dekapitator/Gorod/Trepalium/Skyclad/Ram-Zet/AlexBrachet/DerekSherinian/G-anx/Carcass/Exhumed/InsectWarfare/TheoryinPractice/SergeiProkofiev/JohannesSebatianBach/Nevermore/Centinex/Trollfest/Hypocrisy/Stormwarrior/ClandestineBlaze/Viron/WeCameWithBrokenTeeth/Skeptix/SigArTyr/Tyr/!T.O.O.H.!/CarnalDiafragma/SpasticInk/Atheist/Watchtower/Absu/Equilibrium/Bludwulf/Leviathan/Gorgasm/Arkona/Rossomahaar/etcetera