Flush said:
Sagubooru is written in Flex, which is the language Flash is written in. The decision was met with a fair amount of skepticism when Sag made it, and obviously still is. Considering the current build is labeled as pre-alpha it's actually not too bad, but I do like the current interface much better (though I'm not much of a fan of RoR either).
Flash is not written in Flex. Flex is a set of technologies that make creating internet applications that use flash, easier.