I'm going to keep this as brief and simple as possible:

Our company is thinking of getting two dedicated linux servers, and I'm thinking of a way to have the second one backing the first. I want to run it past you cats and see if you think it'll work before we spend the money... I figure it'll work like this (IPs are just for example):

www.domain.com > 192.168.1.34
Server 1:
192.168.1.34
192.168.1.35
Server 2:
192.168.1.36
192.168.1.37

I figure if the second one pings the first one's 35 address, and when it can't reach it changes its primary (36) address to 34 until it can ping the 35 address and then changes it back to 36.

Server 2 accepts orders until Server 1 is reachable again, copies them over and deletes its own copies. Does this all sound feasible?

If there's such a thing as software load balancing, that'd be a possibility.

You can do load ballancing but unless you are really running under heavy load failover is probably what you are looking for.

There is a lot of good info at:
http://www.linux-ha.org/

Take a look at the "IP Address Takeover" link.

Thank you, thank you, thank you.