I'd encourage you to "watermark" your pictures. You may not like the technique that I use, but you really should do something. It doesn't have to be big, but it should be visible and readable when the picture is shown at 500 pixels across - the Flickr "medium" size.
And, I'd encourage showing not just your names or initials, but your web page address as well. What, you don't have one of those? Geez. Get one. It's pretty cheap and even if you can't get "bobjones.com" anymore, you can probably get bobjonesphotography.com. The problem is that having just your name or your initials will not help people find you. If you've got a common name, like Bob Jones, even if they Google you, it'll be needle in a haystack time. And don't think that having a Facebook or LinkedIn profile will help. People can't see much without going through hoops. But a web page? No problem. So get one!
Even if you have nothing more than a few portfolio pictures and contact information with a link to your Flickr account, that's enough. I've had several people find me because someone stole one of my pictures that was watermarked. People could clearly see where it came from and visited my site.
Yes, people can crop out or obliterate the watermark. But that doesn't happen very often, particularly if you make it big enough that it can be read at 500 pixels. In most cases the "theft" is more a function of laziness on the part of the thief than malevolence. They're not going to go through the rigmarole of getting rid of your watermark. They just want to put your picture on their web page. Which means people will find you. It's gotten to the point now where it doesn't bother me as much when someone lifts my picture. Because, with that jimfrazier.com text in the corner, it's like free advertising.
But what about the malevolent pirate intent on stealing your intellectual property? What if he does get rid of the watermark? Well, if you look at the above picture, I now always put a second, hidden watermark someplace in the picture. In this case, it's not so hidden. I'm usually better at concealing it. Now the jerk really has to do some work to retouch the hidden watermark out of the picture. Even if he does, I can enjoy the warm feeling that he had to break a sweat. And since I don't usually post pictures that are much bigger than 800 or 900 pixels across, I'm not too worried about someone stealing the picture and printing or publishing it.
But Jim! Watermarking is so ugly! So what? You can be elegant about it. Here's one from Aldo Risolvo. His watermark almost enhances the picture. Me, I'm not so elegant. But it doesn't have to be ugly if you don't want it to be. And if the watermark bothers the occasional photographic purist, well, it's my picture - so there (sticking my tongue out).
You might have noticed that Aldo doesn't put his web address on the picture. He doesn't need to. Try Googling Aldo Risolvo and you'll see what I mean. But Bob Jones?
So there you have it. I'd encourage you to watermark your pictures. It'll help people find you. And it goes a long way towards preventing theft. Or at least helping you take advantage of thieves.