How to achieve Large Type like Address Book?

Question

Within Address Book you can click on a contact's phone number label and select the option 'Large Type' which displays the phone number in large text in what appears to be an HUD window. I saw one other application use this but cannot figure out how to achieve this.

What really interests me is

1. how they have the titlebar-less window.
2. the text has a drop shadow
3. the font size shrinks to fit if it's really long.

The only way I was thinking of doing this is creating a regular HUD window, and manually coding something that determines the size of font to show depending on how many characters.