My vs Your

While designing websites, you will be faced with this problem. Do you call things as "My preferences", "Your preferences" or just "Preferences". Substitute the word "preferences" with "Account", "Inbox", "Yahoo!/MSN".

Amazon uses "Your Account", "Your cart". It also uses "Add to Wish List", "Track Packages"
MSN uses "My MSN", "My Calendar", a few your and some neutral. The newer Hotmail and Live strives to be neutral.
Yahoo! uses My and neutral.
Google prefers neutral.
Southwest predominantly uses "your".

I was wondering if there is a guideline on this. I searched around and could not find any. So, let me make a case and you tell me if you buy it.

FIRST RULE: Be consistent (applicable mostly to small sites)
A site that uses all 3 forms thoughtlessly, looks unprofessional

SECOND RULE: If your site can't be customized/personalized - use neutral
This is slightly risky. Eventually, if your site grows in popularity, you might have to add customizable/personalizable parts.

THIRD RULE: If your site site automatically adjusts itself to the users - stay on neutral
By using past history, if you alter the site, then stay neutral.

FOURTH RULE: If your site allows users to change settings to suit themselves, then call those parts as "My"
If users can choose a different color for the skin of the site and they expect that you will remember this the next time, they return, it's a good choice to call these as "My ..."

FIFTH RULE: If you are exchanging money then use "your" for the things the user got in exchange for their money.
If I pay $$$ for an airline ticket, I expect that the site reliquish ownership of the ticket and start attributing the ticket to me. "Print your itinerary", "Change your reservation"...

Try these rules in your specific situations and let me know if these seem to make sense?