Amazon S3 can be a ridiculously safe and cheap way to store your important data. Some of the most important data in the world is saved in... MySQL, and surely mine is quite important, so I needed such a script.
If you have a 500mb database (that's 10 times larger than any small site), with the priciest plan, keeping 6 backups (two months, two weeks, two days) costs $0.42 a month ($0.14GB/month). With 99.999999999% durability and 99.99% availability. Uploads are free, downloads would happen only in case you actually need to retrieve the backup (which hopefully won't be needed, but first GB is free, and over that $0.12/GB).
Even better: you get one free year up to 5GB storage and 15GB download. And, if you don't care about all the durability, later you can get the cheaper plan and spend $0.093GB/month.
The cons: you need to give them your credit card number. If you're like me, Amazon already has it anyway.
Another thing that is real nice: HTTPS connection and GPG encryption through s3cmd. Theorically it's safe enough.
Setup
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1. Register for Amazon AWS (yes, it asks for credit card)
2. Install s3cmd (following commands are for debian/ubuntu, but you can find how-to for other Linux distributions on [s3tools.org/repositories](http://s3tools.org/repositories))