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.
jTDS supports ConnectionPoolDataSource if memory serves, if you want to hook it into a servlet container or app server. I'm sure you can find the class name of the pooled connection class in the documentation.
Alternatively, Apache Commons DBCP is a common choice for the pool implementation.