Fallback / redundant linode - possibilities?

I'm wondering if there's a way I can have 2 linodes, one mirroring the other, for the purpose of providing some redundancy should one of my servers become unavailable.

What sort of tools would I require for this?

Ideally I'd like to avoid having a "central point of failure", so my ideas about having some sort of gateway server that determines which node is up, etc. probably would not be adequate in this respect.

Basically, I just want some way to mirror the servers contents, and be able to redirect requests from one node to the other if it fails.

Only way I can see that working is via DNS, but given that most computers cache DNS entries that also does not seem viable.

Any ideas?