Agreed.  Every app seems to have a slightly different authentication/authorization/identity model. Docs works differently than Analytics, works differently than Ad Manager, works differently than Feedburner.  I'm currently managing 3 "Google Accounts" right now to work-around these mismatched identity patterns and am using one <i>shared</i> Google Account to manage Feedburner, which has a one:one Google Account:Feed pattern (which really irks me). Webmaster Tools is also one:one but at least you can independently authorize multiple accounts...