https://aws.amazon.com/glacier/
Edit: If you are accessing your backsups often, glacier is not for you - but you can't beat the pricing.
For regular stuff, like important shit on your local machines, I use idrive.com since it does continious backups. Been using them for years now, restore works like a charm.
I'm on a PC. No idea what's good for Macs if you are one of them.