Ive never heard of such a safe, and if one existed i would be willing to bet my kidney that it would cost a LOT of cash. Obviously you cant drill a safe and stick cords through it as that would take away any fire protection the safe offered. so lets look at some alternative options that are much cheaper.
Also are you looking to encrypt your data? if so i can recommend a good encryption program.
probably the easiest full proof way to make sure your data doesnt get destroyed is to back it up online, their are many services that offer this sort of service for a nominal fee.
Online Backup - IDrive - Remote Data Backup - For Windows and Mac - IDrive Portable Hard Drive (http://www.idrive.com/?gclid=CIbY7tClkpkCFQ-bnAodWRhobg)
2 gigs free, and if you need more space its a cheap monthly fee. this is a rather good option, though im sure other users will post other sites, so its up to you which you might want to use. Another option would be to periodically make cd/dvd/tumbdrive/external drive backups and keep them off site(at a friend/relatives house, safety deposit box if its SUPER important) this way data loss will be kept to a minimum. but also doesnt take up much space. the down side to this is it will cost gas and time to go back and forth to deposit your backups. if its a location you go to regularly anyway then its no big loss(like say you belong to a country club and you go their every saturday) so that its not a waste of time/gas just a quick drop off or pickup. Though using online storage saves a lot of time and effort.
dont think i missed anything but if i did feel free to ask more questions