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.
Yes, all connection pools allow to set a minimum and maximum pool size (as well as some other options). Check the documentation of whichever one you're using (Apache DBCP has recently come back to life).