Tokyo Cabinet and Kyoto Cabinet
Tokyo Cabinet and Kyoto Cabinet are two libraries of routines for managing key-value databases. Tokyo Cabinet was sponsored by the Japanese social networking site Mixi, and was a multithreaded embedded database manager and was announced by its authors as "a modern implementation of DBM". Kyoto Cabinet is the designated successor of Tokyo Cabinet.
Tokyo Cabinet features on-disk B+ trees and hash tables for key-value storage, with "some" support for transactions.
