...little things at my local Target:
Spot Dots! They're little cushion spots that you just stick on where there is rubbing in your shoe. They are AWESOME. I have hyper-sensitive feet and have tried every cushion there is known to humankind. There are other (cheaper) options, like the little gel ones or moleskin which do generally work, but these are actually much more effective. I had one pair of shoes where I just could not get the rubbing to stop no matter what gel spot or moleskin I put in there, but these finally put a stop to it! They are by Fab Feet (Foot Petals brand) and are $5.29 for six. They seem a little pricey for little dots, but so worth it, IMO. I'm stocking up.