This could help a team of developers working on a project to collaborate on a design (real-time multiuser table editing maybe?) or keep track of revisions/branches to the data model. Think Writeboard for databases. Make a premium version that generates change scripts and sell it for $10/user/month. I wish I had done it first! Great job, Mr. Žára!
Why don't you make it a business, Ondřej?
Btw. you also did some pretty amazing other stuff