DrJava's "interaction pane" seems to work even better than BeanShell for me. it's a larger download, since DrJava is a fairly complete
IDE with a lot of bells and whistles beside just the interactive evaluation prompt, but it's still reasonably small, and the language interpreted at that command line seems to be a bit closer to "proper" Java than what BeanShell implements. after evaluation, i suspect i'll end up sticking with DrJava. thanks everyone!