I'd like to introduce MacWallet.
A tiny and integrated thin client wallet app based on bitcoinj.
Main focus of the app:
-> Small and integrated wallet app for Mac OSX.
-> Low memory and cpu footprint, can be run in background without pain
-> Use Mac OSX keychain as wallet store (by default encrypted with your login credentials)
-> Simple UI. Use status menu (a.k.a global menu) as main UI entry point
Currently, MacWallet app is in early development stage.
Check the bitcointalk post: