Extending the Pasteboard
Butler's "Recent Pasteboards" Smart Items let you access items you have previously stored in your pasteboard (a.k.a. clipboard), effectively turning your pasteboard into a stack. You can also take a snapshot of your current pasteboard and keep it for good by creating a "Custom Pasteboard" Smart Item.
The screenshot at hand shows the pasteboards window Butler displays whenever you trigger a "Recent pasteboards: Window" Smart Item. There, you can paste any recent pasteboard by double-clicking on it or hitting the corresponding key (as shown in the lower right corner of each pasteboard field — e.g., "1" for "http://manytricks.com/butler"). You can also reorder your recent pasteboards via drag & drop.
Go to Butler's "Pasteboard" preferences to specify the number of recent pasteboards Butler is supposed to remember.