I was first introduced to the foam roller in Jiujitsu class. They’re awesome. I suppose there are other ways to use them, but I have been using them primarily as a massage tool. Since I have been doing rehab on my knee I have been using the foam roller to massage my legs and IT band.
According to my therapist IT bands are pretty tough to stretch. So the foam roller is an awesome tool to loosen up those tight IT bands.
You can use them for your legs, shoulders, back and so on. I recommend getting one to help sooth your aches and pains.