The various Ajax toolkits and Flex. The advantage of Laszlo is that its multi-platform, so a single source code can execute on either the DHTML or Flash platforms. You can even create hybrid applications that run on both platforms. You might wonder what's the advantage of a hybrid application? This allows DHTML applications to have compartmentalized Flash modules to supply multi-media capabilties and allows Flash applications to have front-end HTML modules that are easily searchable by web crawlers.