- Pick the folder you wish to hide, then move it to a place that you can remember easily, and whose path you can type quickly. Just inside your home folder works well, ~/Folder is easy and quick.
- Use the Terminal to add a period in front of the secret folder's name, rendering it invisible to the Unmodified Finder, Spotlight and the Terminal (unless ls -a is used). For example, to hide the folder "secret" in your Home folder, open the terminal and type mv ~/secret ~/.secret, then press Return.
- To later access to the folder quickly, just type Command-Shift-G in the Finder to access the "Go to Folder..." window, then type the path to the file. In our example above, that's ~/.secret; press Return when done. That's it; you can now enjoy your normally functioning Finder Window containing the contents of the folder, fully editable and unconcealed, which will disappear into the void again when closed.
[robg adds: When I worked in an office, I stopped casual snooping by just locking the keyboard whenever I stepped away. However, if that doesn't work for you for some reason, then simple hiding as explained in this hint could help.]

