I'd add my recommendation for Ant. I have tried a lot of the Jakarta projects, but the only ones which I use every day are Ant, Xerces and Xalan - and I only use Xerces and Xalan because they integrate so well with Ant!
Ant is extremely powerful and flexible, and I have completely eliminated any manual steps in the development and deployment of software. XSLT processing, templating, compilation,
unit testing , "jar" and "war"-ing, ftp transfers, remote deployment, server restarts, email notification and version control - all with one command!
If you haven't done so yet, I strongly suggest giving Ant a try - you might never look back.