This proved quite a bit tougher than I expected, actually, but I have an answer for you. First off, here's the icon you're talking about:

For those of you that don't know, it's a pretty icon for a basic piece of Mac OS X functionality: a URL shortcut in your Dock (the equivalent of the Windows Start Bar). Let me show you where the icon is located in Mac OS X, then I'll show you how to create a shortcut and apply that icon.

The fastest way I know to find the icon is to simply copy and paste the following bold text into Terminal.app, an application you can find in Applications -> Utilities on your Mac:

What it will do is open up the spring icon in the Preview application:

That's the icon you seek. Now, to use it...

In Safari, go to a page you want to bookmark - perhaps the AskDaveTaylor home page -- and drag the little icon out of the Address Bar (or the tab for the page if you're in multi-tab mode) onto the desktop. In process it'll look like this:

and when you drop it, it'll convert into this:

Almost there. Now we just need to change the icon, which can be done by going back into Preview and choosing Edit -> Copy, then going to the desktop shortcut, clicking it once, then choosing File -> Get Info. You'll see this:

Now click on the icon in the top left of the Get Info window and, oh so subtly, you'll see it get a small highlight. That means it's selected. Choose Edit -> Paste and it'll change to the spring icon, both in the Get Info box and on the desktop. Hurray!

That's all the hard work. Now just drag it onto the Dock itself and drop it where you'd prefer:

Caveat: It's not exactly right because we lost the transparent background of the spring icon (in fact you probably need to use an icon editor to copy and paste the PNG image while retaining the transparency. I'm sure something like GraphicConverter could do it). Nonetheless, that should be 98% of what you seek and I'll leave the nuances up to the reader. :-)