Ok got it - I thought you were talking about load balancing, but if I get you right you mean an (almost) real-time backup system with the ability to redirect the traffic to the backup server in emergency cases?
We're doing daily backups anyway, but that of course doesn't help very much in a situation like yesterday.
Wow, just took a look... not exactly freeware, hehe.
"Never argue with an idiot. People won't know who's who."