Bitcoin Wallet Unsynched and Lost BTC?
Do you know your Bitcoin address?

Check on https://blockchain.info/ that it still has a value.

Locate wallet.dat, it should be in ~/Library/Application Support/Bitcoin/.

Install MultiBit and get a new address. 

Visit https://blockchain.info/wallet/import-wallet. Drag the wallet.dat file into the dotted area. Follow the instructions.

Send your coins from blockchain.info to your new MultiBit address.

You'll now be in control of your coins again without requiring huge blockchain downloads.