Lock 4 Me is an awesome app for Mac OS X(Snow Leopard & Lion), can protect your privacy in other apps that don't have password protection.
For example, evernote or your other apps that doesn't have password to protect your privacy, you can use Lock for Me to protect it, once some opens evernote or other apps, Lock for Me will ask password first, if he/she doesn't know the password, he/she can see nothing in evernote.
***Make sure you've set password before using Lock for Me****
Note:
1. Lock for Me will only be triggered after an app quits completely(Command + Q), then reopen. if you click 'close' button on the left top corner, that will only close the window, the app isn't quit, after that you open the app, Lock for Me will not be triggered.
2. For the files that can be open by multiple apps, for example, pictures can be open by Preview, iPhoto, etc. it's not a good idea to protect them using Lock for Me.