You can use just about any object as a button by making use of the OnClick event. You could make a button that looks exactly how you want by creating a graphic image in Photoshop/Gimp/Paint/whatever, placing it on your form, and using the OnClick event to make it behave as a button. Note, however, that your activation area will still always be rectangular. There are a couple custom controls for other button shapes on the web if it's something you feel really strongly about...
--Square Mac