I'm the primary author of the LLVM Compiler Infrastructure, an ambitious project to build a system of reusable compiler components that let you build all kinds of tools: compilers, debuggers, JIT systems, optimizers, static analysis systems, etc. In its current form, LLVM is most often used as an aggressive optimizer for C and C++, which can produce machine code for X86, ARM, PowerPC, Sparc, Alpha, and several other targets. LLVM is being extended and enhanced in a tremendous number of directions to support new optimizations, new targets, new domains, and to get new features. We hope to make it the future of open source compiler development. If you're interested, please join us!