Good idea, good enough that it's already planned for the next version of Scratch, version 2.0. Scratch 2.0 will have an online project creator and a downloadable version for those who like it that way.
As this has already been planned, there's no use discussing it, and I'll ask for a moderator to close it for ya.
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The Scratch Team is actually planning that for Scratch 2.0; you'll be able to make and store Scratch projects online when Scratch 2.0 is released.
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