SpringDial puts speed dials of your contacts on the SpringBoard of a jailbroken iPhone. The advantage of this is over using the Webclip method is that it is more of a true speed dial. Safari doesn’t have to load, and you are not asked to confirm the call. If you happen to have a photo for the contact in your Address Book (don’t know what Apple is doing for windows users, so this is probably only available for Mac OSX users, but you can edit the contact on the iPhone to add a photo), then it is what is used as the icon for the contact.

http://springdial.mineshaftgap.net/