We've had some hints about finding iCloud documents in the Finder. This hint shows where they are located, and how to navigate through the various local folders that contain them. Both a comment to that hint and an anonymous submission point out how to make a saved search for documents in the cloud.
Go to the ~/Library/Mobile Documents folder. Type anything in the search field in your Finder window. Make sure that Mobile Documents is selected in the Search bar, not This Mac.
Next, click on the + icon, and choose Kind is Document. Go back to the search field and erase what you typed. Now all your iCloud documents will display.
Click on Save, and check Add to Sidebar to add this search to your Finder window sidebars.
Note: one submission said to type a period (.), and, while this starts the search, this may not find all your documents if extensions are not visible. So it's best to start a search, then choose Kind is Document and delete the search.
Note also that you may end up with documents here that you cannot view or edit. For example, I use the ToDo task manager, and its file shows up, but it is not a file that I can edit. Interestingly, I found three Pages documents, each a size of 0 bytes, that don't show up in Page's iCloud panel, so this may also be a way of cleaning out extraneous files from this folder.
Mac OS X Hints