I've worked at Google since 2005. Ostensibly I work on building the web index, but, in practice, I build large storage systems. You can read about one we published in OSDI: Percolator (slides). It was used to build a new indexing system (named "Caffeine" externally) that processes documents individually instead of in large batches. The image above was our official blog's attempt at explaining the system. Apparently in Caffeine you become the nucleus to the web's electron cloud.