IDA: About – Hex-Rays
https://www.hex-rays.com/products/ida/
The Online Disassembler: ODA
www.onlinedisassembler.com/
Retargetable Decompiler
decompiler.fit.vutbr.cz/
Reverse Engineering Compiler – Backer Street
www.backerstreet.com/rec/rec.htm
mentioned by Jason Geffner on http://reverseengineering.stackexchange.com/questions/6952/question-about-x64-decompiler
Boomerang
boomerang.sourceforge.net/
Kurzer Hinweis: Der ODA ist nicht erreichbar?!?
Works for me.