Update (June 21, 2007): I’ve deleted the links to the jQuery.focus() plugin and jQuery page (for now). You’ll find BlockUI to be a MUCH better and MORE complete jQuery solution. I’ve removed jQuery.focus() out of humility.
If you look in the new jQuery tab you’ll see my first released plugin for jQuery: jQuery.focus(). I know, jQuery already has a .focus() method. But that only works on ’s, now it works for everything! It creates a nice fade effect that blocks out everything on site EXCEPT for the element you .focus(). Click here to see a demonstration and please let me know if you find this useful.