If you are a web developer or webmaster, you have probably gone to sites where there are some pretty cool, modern looking, effects. You hear buzzwords like web 2.0 thrown around all of the time. You’re told to round your corners, use prototype, use script.aculo.us, etc.
If you just want to tip toe into this arena, and have wanted to create a cool and simple way to display larger images when a thumbnail is clicked, you should check out litebox.
Rather than rehash everything that is covered so well at doknowevil.net, I recommend that you head over and download the litebox code.