If this is your summer to volunteer on an archaeological excavation, then a great resource is FindADig.com from the Biblical Archaeology Society.  Many digs around Israel and in other countries are listed, with details on dates, cost, and requirements.  There are many good options, but if pressed my top recommendations would be Hazor, Gezer, and Gath.  If you don’t have much money or time, check out the Temple Mount sifting operation.  Most excavations are summer projects, but you can dig on Mount Zion in March.

Excavations at Gezer, June 2006