BusyBox has to be one of the coolest tools I've seen in a long time.  It's this ultra-configurable "waiting" dialog box that you can drop on a page, add an httphandler registration to web.config and every postback of a page the box is displayed.  This is awesome for long running processes that don't update the UI, hell, it's awesome for simple processes too.

What's nicer?  If you've got some sort of inherited control structure in your pages (say, header/footer usercontrols or whatever) you can drop this in the header and now you've got that functionality on every page in your site.

I've not put this through the ringer but my initial impressions are very favorable.