Nice review of three tools for managing multiple sites in wordpress. spoiler alert: I excerpted the winner, but YMMV
I saved the best for last! InfiniteWP is a little trickier to set up because you need to upload files to your server, but it is so worth it! First of all, InfiniteWP is FREE! And, second of all, since you’re hosting it on your server, you’re not dependent on a third-party service and you have more control over the security.
And, guess what! InfiniteWP is FREE!