how big is the set of applications that are both interesting and not so complicated that it'd be more appropriate to use a more traditional environment/language

how big is the set of applications that are both interesting and not so complicated that it'd be more appropriate to use a more traditional environment/language where you have more power/control. Basically every Facebook app, for one. There's also a big niche for hobby programmers who want to make one-off online tools. The code sharing makes that even easier.