You can store serialized, nested structures in Couchbase, such as by using encodings like JSON or XML (or Google Protocol Buffers or Thrift). A user profile item stored in Couchbase can then track information such as user interests. For example, in JSON:

{ "key": "user-1234", "handle": "bobama", "avatarURL": ...,
"interests": [ "A", "B", "X", "W" ], "groups": [ 1, 3, 5 ], ...
        }

If the above is stored in Couchbase under document ID "user-1234", you can then know the interests for that user by doing a simple GET for user-1234 and decoding the JSON response.