I have to agree. I've gotten so many endorsements from non-software engineers who I've never worked with for my apparent XML abilities. I literally don't know what to think about that.
The "endorsement" system is an utter joke. When it was implemented, "endorsing" people consisted of clicking on any and every little oval that was in front of the user. I bet everyone here has been endorsed for multiple things they are unassociated with.
The idea that someone thought that a real-life, personal "endorsement" could be recreated by clicking a button that half the population won't read is beyond me.
LinkedIn seems to be useful because it's hot (as in, everyone is there). But outside of that original, clever idea (a professional social network) it doesn't offer much outside of its network effect.
(BTW It's slipped to #9 now... if anybody wants to endorse me for coffee that would be lovely ;-)
A previous boss endorsed me for PHP, at that job I used PHP exactly 0 times. Needless to say, he wasn't a very good boss either.