It would be immensely useful if Google understood that normal people have multiple facades that they use in different contexts. Probably several professional (which project / component was I working on again), private but family friendly (planning gifts for relatives, etc), and private but clearly out there (stuff you don't want to shock 60 year old parents / young kids / etc with) profiles.

Also, for incognito stuff, it'd be nice to have read-only basing on stock profiles related to various activities or people.