Mac OS 10.7 and 10.8 default to hiding the users Library directory, this is probably to keep people from accidentally deleting or damaging files that are necessary for OS X Lion to function properly. That is fine for novice users, but for some of us, we want to be able to access ~/Library/ at will. A visible Library folder was also the default setting in past versions of Mac OS X, here is how to get this back.

Show User ~/Library in OS X Lion & Mountain Lion

Launch Terminal from /Applications/Utilities, and enter the following command to show or hide the directory:
chflags nohidden ~/Library/

The users Library folder will immediately become visible again. Reverting this back to the standard Lion setting is simple too:

Hide User ~/Library in OS X Lion (default setting)

This returns to the default setting of hiding the user Library directory:
chflags hidden ~/Library

Changes take effect immediately again, and Library becomes invisible to the user.