SLopen automates the changing of the preferred application for documents to open with to that of their creating application so that double clicking the document on Mac OS X 10.6 Snow Leopard causes the creating application to open the document and not the system default application for the document's file type.
The problem: Mac OS X 10.6 Snow Leopard no longer respects the creator code of document files. When double clicked, such files now open using the default application for the file's type and not the creating application. In other words, the "when I double click a document in Snow Leopard, I want it to open under not " problem. For example, you want your Photoshop-created PNG files opened by Photoshop, not by Preview.
Solution: change the "Opens with" setting for all document files to that of the creating application. You can do this by hand but if you have a lot of documents, this can get tedious. This program can automate the process for you. Note that this is really a work-around and not a true solution to the problem but for most people, this work-around will probably be sufficient.
This problem can only be properly solved by storing the preferred application's bundle identifier as metadata with the document. Until that solution is implemented by Apple, changing the "Opens with" setting is the best known work-around for the problem.