This week's giveaway is in the EJB and other Java EE Technologies forum. We're giving away four copies of EJB 3 in Action and have Debu Panda, Reza Rahman, Ryan Cuprak, and Michael Remijan on-line! See this thread for details.
Well, specifically Vector and HashTable are synchronized. All the other collection classes are unsynchronized. However, you can obtain a synchronized wrapper for the collection classes via the Collections class; but the default implementations are all unsynchronized (except for Vector and HashTable)