MIPS - Compiler, Assembler, Simulator

Compiler:
lcc, A Retargetable Compiler for ANSI C
http://www.cs.princeton.edu/software/lcc/

Assembler, Simulator:
SPIM: A MIPS32 Simulator
http://www.cs.wisc.edu/~larus/spim.html

MARS (MIPS Assembler and Runtime Simulator)
http://courses.missouristate.edu/KenVollmar/MARS/