Shrink your JAR

Releasing your small project / library into public? Think about shrinking it beforehand - it's always nice to save some bandwidth if possible. There is nice (free!) tool for this purpose - ProGuard. Results, as published on the web, are quite encouraging. For example Apache Ant went down to 242K from 2.4M and that's staggering 90%.
What's more, ProGuard can do more that mere shrinking. Dead code listing (optimization) and obfuscation all come bundled.
To sum up, one quick run of this handy tool can make your release smaller and less prone to reverse-engineering. Give it a try!