I didn't know this until Kewfriend just told me, and it really quite surprised me. If you have a Barclaycard, you can view your PIN online. You have to be registered for "mybarclaycard", and I'm glad to say, I am not. So I can't tell you what actually happens when you use his "service".
Because I'm not registered for "mybarclaycard", I don't know what precautions they take before displaying your PIN number to whoever is able to log in to your "mybarclaycard", but I rather suspect that they aren't enough, because to my eyes, banks are generally pretty poor at security.
As a general thing, I'm very wary about online banking. Of course, it's difficult to live these days without spending money online, so here's what I do.
1) I don't do online banking.
2) I mostly buy things via Ebay, who have a confilct resolution system that's been good to me in the past.
3) I use Paypal, but the Paypal account is fed from a credit card. That way, if anything naughty happens, I can appeal to Paypal to sort it out, and I also have the protections that you get with a credit card. You don't get anywhere near as good protections with a debit card, or by linking Paypal to your bank account. So I can also appeal to my credit card provider to sort it out.
4) I only give my credit card number to Paypal, Amazon and a very small number of companies that I've dealt with a lot in the past. And NEVER to any company that doesn't give their address and phone number on their web site.
I'm always surprised that people are willing to give details to companies that don't seem to want to give out an address and phone number.
So what raised my awareness of this? Kewfriend (that's his Facebook name) has had an identity theft. They got a couple of his email addresses, his Paypal password, and I can't remember what else, and it was only because Paypal sent several messages to his email, that got pushed to his Blackberry, that he knew that anything was amiss. He acted fast, and hasn't actually made a loss, except of time and trouble, and the hassle of having to call banks and notify people and change passwords and reformatting his computer and reloading it.
There's a lot of ways this identity theft can happen. Using the same password on multiple sites is one, and getting a trojan installed on your computer is another. Kewfriend wasn't using the same password everywhere, but he was using Windows, and now he's switching to Linux for most purposes. You can read his posts on Facebook.