As regular readers, and our customers will know, we've been quite smitten with NoSQL databases, and MongoDB in particular, for quite some times. The combination of speed and flexibility perfectly matches the type of problems we solve on a daily basis. SQL DB's such MySQL, Oracle or MS SQL would provide limited scaling in these sorts of problems.
Recently, we became aware of a new kid on the block, Membase. Membase has already picked up a lot of heat in it's short lifespan. It is a new distributed key-value NoSQL competitor, featuring a memcache compatible interface, yet is persistent like a database.
We'll be taking it for a spin soon, and will try and get some real performance numbers to report back on.