There's no charge for "signing up." Unless you need more than the six GB limit you can get from friends & neighbors.
As for splitting large files, I'm willing to bet there is at least one app for the Mac that can do that. I'd recommend a Google search... On the other hand, with a free service like DropBox, there's no need to do any splitting and then making the recipient re-connect them. :dknw:
Not having to do that is sort of the point of using DropBox for file transfers.