From Xilinus.com: Prototype Javascript Windows These are the best JavaScript/Ajax popup windows I've ever seen... I'm going to ditch my custom-built ones (which have some unfortunate limitations like no resizing) and redo them with this baby as soon as I can! The library uses prototype and is "inspired by" script.aculo.us, which you can use as an option. These were originally released in March and have now been updated to the latest and greatest prototype/script.aculo.us libraries.