There is nothing quite like learning by example and Pete Freitag has kindly pointed to a few of his examples on accessing Java methods from within ColdFusion MX.
- How to make ColdFusion MX go to sleep
- ColdFusion Memory Usage Stats
- Using Java Web Services with CFMX
- Getting the server hostname programmatically
- Checking your JDBC Driver Version
For more info on all the Java methods available to cfmx look no further than the Java Api documentation.