This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
Most all of Hashtable's methods are synchronized to make them (mostly) thread-safe. If you don't need thread-safety (or need finer-grained control), HashMap is your friend. Java 1.5 also added ConcurrentHashMap (or some similar name) that I believe allows multiple readers simultaneously.