ASM plugin for eclipse found here works neat upto Eclipse 3.3
If you have updated to Eclipse Ganymede, you will see that it no longer works. It complains something like:
Error (Bytecode Outline) src/Foo.java [in BarProject] is not on its project's build path.
Where Foo.java is the java class for which you want to view the bytecode and MyProject is the eclipse project in which it is present.
After a little bit of googling found out that a new version of the plugin is available for Eclipse Ganymede. You can get the new version at http://andrei.gmxhome.de/bytecode/index.html. Use http://andrei.gmxhome.de/eclipse/ as the update URL with the update manager and install the new version.
Works cool now :)