<p>I'm working on a web application that needs to prints silently -- that is without user involvement.  What's the best way to accomplish this?  It doesn't like it can be done with strictly with Javascript, nor Flash and/or AIR.  The closest I've seen involves a Java applet.</p>

<p>I can understand why it would a Bad Idea for just any website to be able to do this.  This specific instance is for an internal application, and it's perfectly acceptable if the user needs to add the URL to a trusted site list, install an addon, etc.</p>

I have to be honest, I am kinda thinking out loud here.. But could it not be done with  an applet or some sort (be it Java or whatever) that is given trusted permissions (such as that within the Intranet zone) or something?
May be worth investigating what permissions can be given to each zone?
Following a Google, I think you definately have a challenge, so far most of the articles I have seen involve printing to
printers connected to the server
.
If its internal, would it be possible to route printing from the server to department/user printers or something?