The music I listen varies greatly and is directly influenced by the type of scene I'm writing. Generally, though, I'll listen either to Christian Rap (primarily Lecrae, Trip Lee, Tedashii, Flame, J'Son, Thi'sl, etc.), Christian Rock (Skillet, Thousand Foot Krutch, etc.) or instrumentals of soundtracks or specific songs.
Where it gets crazy is when I start writing extensive scenes. For chase scenes, I love using chase themes from various video games or anime (like FFVII: AC Highway Chase Theme and Assassin's Creed Chase Theme). For action scenes, I like listening to anything hard-hitting, like what was listed above, or soundtracks (like The Raid: Redemption soundtrack and Saints Row 3 Soundtrack). It primarily stays around several specific genres: Christian Rap, Christian Rock, Hip Hop and Rock instrumentals, Covers/Remixes, Soundtracks, Dubstep, and ambiance on occasion.
Recently, with a story I'm writing elsewhere, I've been using a lot of NFS game instrumentals and Initial D's soundtrack and instrumentals, because the story is a street racing story. Like I said, it's based on what I'm writing.
As for typing on the forum like what I'm doing now, Lindsey Stirling and Pentatonix (both YouTube artists) are usually in the background. Either that, or Metroid Metal.