My major project at the moment is the National Science Digital Library - the NSDL. I currently manage the group that develops the Metadata Repository, the main aggregated information store that defines what is in the library. I've also worked on the main library portal, programming the search and browse interfaces.
Right now, we are automating the aggregation of metadata from collections, use the OAI-PMH protocol. When this effort is complete, new collections will be able to register with the library and have their catalog metadata automatically harvested on a regular schedule.