The combination of database systems and cloud computing is extremely attractive: unlimited storage capacities, elastic scalability and as-a-Service models seem to be within reach. This talk will give an in-depth survey of existing solutions for cloud databases that evolved in the last years and provide classification and comparison. This includes real-world systems (e.g. Azure Tables, DynamoDB and Parse) as well as research approaches (e.g. RelationalCloud and ElasTras). In practice however, there are some unsolved problems. Network latency, scalable transactions, SLAs, multi-tenancy, abstract data modelling, elastic scalability and polyglot persistence pose daunting tasks for many scenarios. Therefore, we conclude with „Orestes“ a research approach based on well-known techniques such as web caching, Bloom filters and optimistic concurrency control that demonstrates how existing cloud databases can be enhanced to suit specific applications.