I use incognito mode to get Chrome (or Firefox) to pretend to have an empty cookie jar. So that I can log into some site again with a different account, for example.
I stand corrected. No local history + cookies then.
And making sure there is nothing cached
And seeing a website as a first-time visitor to make sure the color of non-visited links is OK
Just an FYI there is a pretty neat chrome extension called Click and Clean, it allows you to whitelist cookies and deletes the rest with the click of a button. Good for web development, etc.
I routinely use it to test alternate logins, given that it behaves as a separate browser session.