This question's only answer provides a solution that requires registration and has associated costs.
Both are anti-open data and should be treated as such, however I know this question will be popular; AWS datasets/public datasets are/will be popular, and the same with AWS usage.
I flagged this for closing because it is at odds with Open Data; Frank (poster) mentioned meta, so here we are.
For what its worth, there are ways to access AWS public datasets (I'm not sure about AWS datasets) without signing up and most certainly without paying a cent for access.
Edit: I don't want to get to pedantic about this. I support the OKFN's definition of open data, and I thought this site did. I've seen the wars on open source stack exchange around semantics and definitions and its truly not worth it to go back and forth constantly. Maybe we just need a formal definition here.
Edit 2: What Would You Pay for Faster Smarter Government Data is a podcast discussing how moving to the cloud can/may/will cost users.