Matt Godbolt posts GCC Explorer - an interactive take on compilation.
One of the things I spend a fair amount of time doing at work is compiling my C/C++ code and looking at the disassembly output. Call me old-fashioned, but I think sometimes the only way to really grok your code is to see what the processor will actually execute. Particularly with some of the newer features of C++11 — lambdas, move constructors, threading primitives etc — it’s nice to be able to see how your elegant code becomes beautiful (and maybe even fairly optimal) machine code.
See github for sources.