Andur said:
Two part post:
1) Are there any good products out there with hit location systems in them?
2) Is there any demand for a multi-tiered (read simple, average, and realistic), cross-platform hit location system?
1) Don't know.
2) Don't know.
What I do know is that 18 years ago, I created an incredibly in-depth random hit location chart based on d100, and it has provided us with a GREAT deal of amusement over the years. It's one extra roll, and it adds depth (and a bit of extra danger) to combat.
It's strictly locations. I leave any mechanical interpretations up to the individual GMs.
By the way... I created this as a 16 year old punk who was pretty intently studying martial arts. About 70% of the targets are called by the latin terms, or what I learned them as in Kung Fu class.
Of course.... studying the chart also helped me pass the target session of the Green Belt test... but that's a side effect.
In my groups, it has withstood the test of time.
It has been alternately praised and ridiculed for the exact same reasons... Because it is so in-depth.
*shrug*
We (my gaming group) like it, and that's all that matters.
As for your fishing for whether or not it would make a decent product.... I highly recommend a random hit location chart for gamers. It does add depth, and a bit more realism. I've found that my players are able to really identify with the wounds their characters are receiving if they know exactly where they're going.
Disclaimer... A product like this may cause you to have to think a bit more. Use caution if you don't like thinking.
Or if you like your combat to be completely abstract, rather than specific.
A hit location chart also pretty much removes the concept of hit points as battle fatigue from the point of view that everyone can only take one or two hits, and everything else is near misses, since you'll be seeing where every hit lands.
Things you have to take into consideration when considering a product of this type.
Also you have to consider whether or not you're going to have mechanical effects of particular hits...
Does a full damage gunshot to the calf cause you to lose movement speed?
Does a knife in the eye affect your hit modifiers?
How about a baseball bat to the throat? Do you want to institute "drowning" rules for the character not being able to breathe?
In a realistic game, these can all add to the color and the flavor of the game.
In an abstract game, it's just more bookkeeping, and more rolls.
Andur... if you're going to create a product with this, I'd be happy to compare notes, or offer ideas, if you want.
Or not if you don't want.

No sweat, either way.