Another review of Cassandra et al.
Uwe Schaefer 
Tuesday, 22nd of September 2009 at 09:57:00 PMi almost missed Redis, but it sounds interesting:
It also has atomic operations. This is honestly the only reason I find this project interesting, because the atomic operation support that it has means that it can be turned into a best-of-breed tally server. If you are building a server to keep real-time counts of various things, you would be remiss to overlook Redis as a very viable option.
