I tend to respond by getting a couple parameters for my answer as there are more than a few different dimensions as to how I could answer that:

Time – Do I have 30 seconds, 2 minutes, 10 minutes, an hour, or more? Different time lengths change what I’d say as more time gives me more content opportunities.

Focus – Do you want a more technical answer in terms of where I got this and that skill or just a general biography of my life up to this point? Now that I know how long I should talk, is there something specific I should be using here.

Armed with those two answers I try to formulate an answer as best I can, but don’t forget that in asking those questions I acknowledge that I don’t want to presume things. This may catch some interviewers off guard or make me think that, “Yeah, I want to talk to you, but I don’t want to waste your time,” as really if you don’t want me rambling on about how I was a cute baby that my parents wanted in show biz, why should I choose to hang myself in this interview already?

Mind you if somebody approached me at a bar told me “Tell me about yourself” I’d assume the guy/gal was clueless about talking to women and attracting them. That would also show how they were inexperienced in dating. “Tell me about yourself” means I have no clue how to talk to you so I’m hoping you’ll help me out by blabbering something.
Sometimes I tease them and say “Are we at a job interview?” because it is so boring and doesn’t make the two people connect with each other.The thing is..I don’t think that question should be even asked at a job interview either!

Hey, Pinar! You used the analogy far better than I did…! And you make the point better, too!

I’m a recruiter, & I happen to be one who likes that question, but in a slightly different form. I’ll ask people to walk me through their professional life, particularly mentioning when & what got them interested in their field. they can start where they want. Look, no matter what flavor of resume one embraces, a well done one is a sterile composite of facts. YOU aren’t in there. I want to know about you too, not just resume stuff.
Actually you should wish they ask as its an opportunity to slide Nick’s advise in. If you can get them to pony up a real life issue, need, task then you connect the dots, you interpret the question as to your professional story, walk them through your resume taking advantage to put some life into it, and then to your last job…and don’t stop, walk your story into their company with you addressing their need.
And yes so it’s a bar question. There is a courtship going on…if you’re really interested in them you want them to fall in love with you. That question is only useless if you don’t use it to your advantage.

Most interviews open with some version of the question ‘Who are you?’, with the usually unstated ‘And I mean in your work life, not your surgeries, divorces, kids…’. The answer should be a *brief* overview of one’s career designed to make the interviewer ask for more detail. The candidate is trying to turn the interview from an interrogation into a conversation. Having watched many, many taped interviews, I can tell you that most people are at their most nervous at the beginning and relax more and more as the interview progresses. If they have a more or less canned 30 second answer to ‘Who are you?’, it gets them past that first hurdle

Given that I’ve been doing technical work for 47+ years, my complete resume would tell far more than any prospective employer needs or wants to know, and much of that info would obsolete or immaterial. Like most people, I find myself fascinating(LOL) but realize others may not. I limit myself to those parts of my past/skills that are pertinent to the job. Believe me – if you hired me, in six months you would know two things: I know and can do my job damn well; I have more ‘war stories’ than Carter had liver pills.
:-)