What is the value of a Coursera certificate?

Value in an academic environment: zero. Everything you learn at Coursera you'd simply learn from a textbook in a few days if you needed it for your academic research or teaching.

Value to a non-academic employer: marginal, mainly as a signaling device (this person will sacrifice his spare time over a non-trivial amount of time to improve himself), but certainly lower than a certification in a field or skill directly related to your job.

Value to a prospective spouse (as suggested by earthling): depends. I'd certainly look favorably on someone who took a Coursera course instead of watching TV.

Value to yourself: again depends, but could be highest of all. I certainly know that those courses I took were mainly for my own pleasure and benefit.

One of the commentators mentioned that MOOCs might be seen in a negative light in some fields, such as software engineering. Especially for this particular field, I would not at all be surprised: Many of the current professionals got their hands-on training through working on projects on the internet in their youth, and such projects would obviously go well beyond a simple introductory course. As such, MOOCs provide only introductory material to the field, and this material has been available in an easy to access format on the internet for a long time, anyway (YouTube tutorial videos predate contemporary MOOCs by years, and simple websites even more so).

I should point out that for other fields, often more specialized in scope, the sort of lectures offered by MOOCs have not been available unless you went to university to study the stuff. Sure, books have existed, but there is a difference in learning from books and listening to lectures (the latter being much more passive, and therefore often more enjoyable, while perhaps not as deep or efficient).

Having said this, I strongly feel that taking MOOCs on your spare time shows that you have motivation to deepen your knowledge, be it in your own profession or just enlarging your horizons and understanding other fields. While reviewing the basics of a field that you are supposed to be an expert in could be viewed in a negative light, a basic understanding of project management and economics would probably help your application even if you were a software engineer.

I have heard some recruiters say that they appreciate an internet presence, and joining in on all the new fun would certainly show that you are technologically capable and follow what is happening in the world. In the software engineering world, one could well put their StackOverflow alias on their CVs. I am sure that some recruiters disagree, though.

Finally, to address your point about how online courses compare with real live universities. Traditional courses usually have a higher workload, and more stringent control on passing a course. MOOCs being very new, it is nigh impossible to know just how difficult it is to pass a particular course or whether you even know the stuff now that you have. Granted, a traditional university degree does not guarantee these things either, but prospective employers better understand how much one can expect one to remember from the courses taken at a real institution. I think MOOCs will play a slightly bigger role in the future than they do now, but we are not quite there yet.

MOOCs like those taught on Coursera are a matter of differing opinions. I think they are great for the students since they provide a great free tool for helping learn content that may be difficult to learn, interpret or even access alone. Unfortunately, they have problems with verification: students do not have to do very much to confirm their identity, and there is much speculation of plagiarism within the classes (even The Guardian wrote a small piece on that recently http://www.theguardian.com/education/2014/mar/14/students-cheating-plagiarism-online).

Have I taken classes on Coursera? Yes. Do I put this on my CV? Yes...for internal purposes anyway, under a "continuing education" or "professional development" section to show my employer that I am continuing to improve myself and stay up-to-date where necessary. I'm a scientist.

My husband (a software engineer) tells me that, while MOOCs or similar training is good on a personal level, it is considered a negative thing for people in his profession, and usually only added to CV to make up for a lack of real technical training or experience. So, unfortunately, I guess the area of your work will make a difference to how others perceive your good intentions. But, yes, Coursera is better than TV!