[FooBarWidget]

What jacquesm said. It depends on the kind of analytics data; our data is not as important as someone else's analyitcs data. For us it's more important writes are of reasonable speed, that we can store the data in arbitrary structures in a schemaless way, that we can define arbitrary search indexes and that the data can be horizontally spread across multiple servers.

Website visit counters are a great example. I don't think many people care if a few visits get lost once in a while.