See the idea can be simple (not overcomplicated), but the harder the implementation the better it is. Dropbox, Mint and Posterous are rather simple ideas, but I

See the idea can be simple (not overcomplicated), but the harder the implementation the better it is. Dropbox, Mint and Posterous are rather simple ideas, but I can guarantee those guys sat around for hours trying to figure how to implement what appears to be so simple to many.