We are currently evaluating a NoSQL solution (HyperTable) for a "datamart" type of application. We have gigabytes of weather observations that need to be searchable by location, date, and observation type. The indexing options are rudimentary at best, but the highly distributed nature and ability to handle gigantic datasets seems like it would be worth the trouble of working the rest of the way through the implementation.

I figure we will probably use a RDBMS for the more complex queries, which will return a key range of sorts for the actual data retrieval from the NoSQL tables. I'd like to hear more about other hybrid solutions that others have tried.