Over at Net-Tuts there are 20 really good AJAX effects you can use on your website or blog. There are my favorites like the LightWindow v2.0, jQuery checkbox and the horizontal image menu. Each AJAX effect provides a demo of the effect as well as the source code to implement it into your site.

Here is a site that provides a javascript class that allows you to create the mouse over notes /tips that you might find on some Flickr images.

According to the site this should work on the following browsers: Internet Explorer 5.5+, Firefox 1.0+, Safari 2.0+, Opera 7.6+. Below are a few image examples of what the script allows you to do with your images.

Regular Image

Mouse Over (you can see the note boxes)

Roll Over Boxes (notes for that area is displayed)