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Off the top of my head, Facebook and Mashable do this, it's becoming the standard.

It doesn't help that most laptops have lost the Page Up/Down key. Just a thought.

Space for page down and shift+space for page up are pretty common too.

I've never seen a full laptop that didn't have a PgUp/PgDn that wasn't a Mac.

Some netbooks do have these keys removed, but certainly not "most" laptops.