SchuchWun
Helping investigators catch child pornographers and/or credit card thieves is a worthy cause. However, I see a few potential problems with respect to Xbox modding.
It is my belief that Xbox modders, while tech savvy, are not child pornographers. Conversely, child pornographers may be somewhat tech savvy, but are not Xbox modders.
That's not to say that there no individuals out there with kiddy porn and/or stolen credit cards on their Xboxes. I just don't think the two profiles coincide to a degree that would make development of specific software tools to find such evidence justifiable. Realistically, it doesn't make good sense.
Also, I have to agree with Wishi that investigating one set of wrong doing while overlooking another could be construed as selective morality. More importantly, from and investigative, or law enforcement perspective, you can't reasonably investigate one without investigating the other. If someone is being investigated for child pornography, but is not a child pornographer, nor has any child pornography on their Xbox, but they do have a few archived games, a legitimate investigator can't just look the other way. Or, can they?
You can't rationalize piracy by saying you believe advancing technology promotes it, or that because child pornography is more serious, that piracy can be overlooked.
Awareness of the fact that modded Xboxes can store files other than what was originally intended is certainly an important factor. That would give investigators another place to look for evidence. Although, it seems to me, investigators would only need a boot disc with boxplorer, or other existing file handling utils, an/or some Linux experience to snoop around for files. As you've heard, you can already map the Xbox hard drive to a networked PC and search from there, too. There are tutorials on this.
I think you can tell from the other resonses that you'll probably find a good deal of reluctance on this here, but only because some members may have some archived games on their Xboxes that they shouldn't.
Helping to catch scumbags --> good cause
Creating highly specialized tools to find little, or no evidence --> probably not a great idea