I've often found it odd that Apple doesn't allow you to embed your .Mac Web Gallery into your website. You can, of course, use the widget to display a thumbnail of your gallery, but it takes users away from your site, and that is a bad thing.
If you use iWeb's HTML snippet found under Web widgets, you can implement an iFrame that will display your web gallery within your page. It is very simple to do and will allow your users to stay on your page while leaving all functions of the site intact. Using the following code, you can inject the Web Gallery onto any page:
Mac OS X Hints
http://hints.macworld.com/article.php?story=2007111620013523