I'd passed over the POI project at Apache's Jakarta before and wasn't horribly impressed, but it's apparently mature enough now to be featured at O'Reilly's OnJava web site.

POI is a way to create and read Microsoft Office docs using Java, which are strange bedfellows indeed. I don't think it'll revolutionize the way many people do business, but it is a nice trick to have in the back of your toolbox (ouch, mixed metaphors).