Who is Quietust?
He is a former member of the NESdev community, though he still occasionally makes minor contributions to this wiki.
What sort of stuff has he done?
He also traced out the RP2A03G die (excluding the 6502 embedded within it) and used the information to make an interactive simulator (based on the Visual 6502 project). His findings suggested that pin 30 enabled 4 additional I/O registers at $4018-$401A, a theory which he later verified using his own CopyNES.
He began to do the same for the RP2C02G, the NTSC NES PPU, though he does not expect it to be complete until mid-to-late 2012 due to unavailability of delayered die shots. Detailed status can be found here.
Where can I contact this 'Quietust' person?
Your best bet would probably be to email him (@gmail.com). He can also be found occasionally on irc.freenode.net using the nickname "_Q".