Redis with Salvatore Sanfilippo Podcast from MyNoSQL by Alex Popescu.
Sanfilippo says that Redis is a key/value database to be sure but from another point of view, it is also specific values that have data models. (?A fifteen minutes introduction to Redis data types)
See the Redis homepage
Which reminds me of a post on the nature of keys that I have been meaning to finish. More on that topic soon.