Creating a Stamps Toolbar

Since you are on Acrobat 7, then yes, there a couple of different things you can do. But unfortunately Acrobat doesn't have anything built-in for easily creating toolbar macros. To do this you'll have to know a bit about Acrobat Scripting.

You can create toolbar buttons with Acrobat JavaScript. There's a tool here that will build the code for you:
http://www.windjack.com/product/acrobuttons/

Next, Each of the stamps has a menu item, and menu items can be run from a script. So, you need to identify the menu item for the stamp and then run it from the code that is run when the toolbar button is pressed.
Here's an article on how to do it:
http://acrobatusers.com/tutorials/2008/06/executing_menu_items_from_javascript

And here's a series of article on everything you ever wanted to know about Stamps in Acrobat and PDF.
http://www.pdfscripting.com/public/department53.cfm