Here’s a great tip over on TipBITS that I didn’t know, but could come in handy some day.

I usually have no need at all for seeing invisible files in the Finder. If I’m doing anything to do with invisible files, I’ll generally just drop straight into the Terminal where I can see what’s really going on.

Although the User’s Library folder is invisible, you can go there via Shift+Cmd+G and typing in ~/Library – and getting into the Library folder is the main reason I need to do anything with an invisible file in the Finder.

If you’re doing something where you really do need to see all invisible files in the finder, there’s a handy keystroke to toggle the setting on and off. Just press Command-Shift-. and the invisible files will be shown.

Source: TipBITS: Reveal Invisible Files on the Mac with a Keystroke – TidBITS