I love scrollable Stickies, but the method of implementing it has changed slightly under Leopard, as there's a brand new Interface Builder in the XCode tools.

Back in December 2005, Rob Griffiths put together a wonderful walk-though on how to create scrollable stickies under earlier versions of OS X. Read through that article (or print it off) to get most of the information you need to do this.

Things change once you open up the StickiesDocument.nib file in Interface Builder. After double clicking on the Window box, press Shift-Command-I to bring up the Inspector ... and it's a very different Inspector from prior versions of Interface Builder.

1. In the Inspector (which should say Stickies Window Attributes at the top), click on the Connections icon in the mini toolbar (it's the fifth one over, represented by a blue circle with right-pointing white arrow).
2. In the Outlets section that appears, double-click on the text labeled Scroll View (not mScrollView). Now, click on the first icon in the mini toolbar (Attributes).
3. In the Scroll View section, check the boxes marked Show Vertical Scrollers and Automatically Hide Scrollers.
4. Now, quit the Interface Builder program, being sure to save when prompted to do so.

That's it! You'll now have Leopard Stickies with scroll bars that automatically appear if there's more text than what the window allows.

[robg adds: The writeup I did for Macworld was based on this hint, which covered a number of other things one could do to Stickies in Interface Builder; I'm not sure how many of those may still be possible.]