If you use a Mac there is a free Dashboard widget called Dashalytics that offers quick access to Google Analytics statistics. You can easily have multiple widgets open to track statistics on multiple sites. Dashalytics also uses the Keychain to securely store your password.

Dashalytics will work with any Mac running OS X 10.4+ specifically using the Dashboard functionality built into Tiger. You also need a Google Analytics account (downloading Dashalytics pointless if you dont).

You can also see Dashalytics 3 in action with this short video: