I am not endorsing any particular barefoot-based products, but here are a few that may interest you.
In the case of products that I have used, I'll tell you what my experience has been, but that assessment may change in the future.
Let me know if you have additional information!
The Nike Free line of running shoes was developed to simulate the flexibilty of the human foot. Nike came up with a criss-cross cleavage pattern on the sole. The thickness of the sole varies according the the Nike Free model number. I use the Nike Free 4.0, pictured here, which appears to have been discontinued by Nike in favor the 3.0 and 5.0 and possibly others.
I use my Nike Frees when I run out of downtown Portland. Once I get into the hills, I stash them in the bushes where I can find them for my return trip. Haven't misplaced them yet!
I also use them during winter days when the ground is frozen, for summer days when the pavement is super-hot and for exploring new courses in places that I am unfamiliar with.
Products - Nike Free 4.0
Product - Vibram Five Fingers
Here is an intriguing product that looks really promising -- the Vibram Five Fingers (not "Five Toes"?? Oh well!). I'm very eager to try it out. The idea is to let you do various activities barefoot, but with skin protection. In other words, skip the foot-toughening phase and go straight to the adventure of barefoot running, hiking, walking, etc. The fancier models have more protection and grooves on the sole that give you traction beyond what the skin on your soles can offer. That opens up activities like rock scrambling, rail-walking and who knows what else!
One price of developing calluses and thicker padding on the feet is cracking around the heel. After showering, I put moisturing creme on my feet to keep them supple. But I've been particularly pleased with these Made-in-Oregon (Sisters, Oregon, to be exact) products my wife discovered a while back: "Life Out", "Healthy Feet" and "Working Hands".
Note: Until it absorbs into the skin, the stuff tends to get on clothes and the carpet. It can be easily washed off, but to save the trouble, I put on a pair of thin socks until it soaks in.