Shawn Whitaker from Insidious Decrepancy / Viral Load. Here's what he had to say about his eight string axe:

"This is fucking beyond sick! (...) I can play dying fetus guitar and slayer bass on the same instrument. Tuning for my 8 string, 8-E flat, 7-G#, 6-C#, 5-F#, 4-B, 3-E, 2-G#,1-C#"

http://www.myspace.com/insidiousdecrepancy
http://www.myspace.com/viralload