...I was wondering if there was an app out there that allowed the tethering of a DSLR camera directly to the iPad without having to use a computer
Since DSLRs are part of proprietary "systems", it's unlikely that a generic remote control app will be available. More likely, the app will have to come from the manufacturer as part of their "system". (i.e.: you can't use all the smart features of Nikon flash with a Canon EOS. So an app to control a Nikon will likely have to come from Nikon.)
The only remote control from an iPad I've seen uses a Canon EOS 5D:
[http://www.photoxels.com/canon-eos-5d-mark-ii-remote-controlled-by-ipad|http:// www.photoxels.com/canon-eos-5d-mark-ii-remote-controlled-by-ipad>
I dont know much more about what equipment was used (I'm not an EOS user) but I can't imagine that it'd be cheap. And in addition, if you're not a EOS user, then you're looking at $2000+ for a EOS 5D body, then add the lenses, flash, etc. BTW, it looks like there's still a "computer" attached to the camera body, but it's more a controller rather than a general purpose PC (which is why I think that it's not going to be cheap.)