Do you mean Java or JavaScript? I haven't had Java installed for a couple of years and have yet to hit a site that doesn't work because it is missing. JavaScript on the other hand is all over the place. The bill pay system on every bank I have used uses JavaScript. The local utilities use JavaScript to present your bill online.
Many companies use Java for their intranet apps. From what I have read, that was the original intent for Java. I know the intranet where I used to work was eat up with it.
Mike