XUL and PHP
Harry Fuecks has posted two Mozilla related articles at phpPatterns() relating XUL to PHP:
Both are great articles in case you're interested in building something like XUL Channels.
Nice XUL demo is also at http://clav.port5.com/cardsonline/cards.xul
Not exactly mind boggling but shows that XUL can be effectively used for anything really. See http://clav.port5.com/ for an extension :-P
Not only is it Solitaire in XUL but it's better than the Microsoft version! Nice that it automatically makes some no-brainer moves for you (with pretty animation to boot).
The best part was that I actually won on my first attempt, something that normally eludes me. And the way that the cards all zoomed into place automatically for the last few moves was far better than the dancing cards you get from Microsoft.