In a medium microwaveable bowl, heat the peanut butter in the microwave oven until melted, about 15-20 seconds (or heat peanut butter over low heat on stove until mushy).
Whisk honey and tamari into the peanut butter, then whisk in the sesame oil and the ginger.
Toss the spaghetti with the sauce, and top with the sesame seeds, if you want to go really groovy with the noodles. If you want to bump up the crunch factor, add some shredded carrots, scallions, bean sprouts or other veggies.