They look a lot like springtails to me. I had them a while back, but I must say the ones I had were jumping all over the place! I read springtails are a large family, so maybe you have a type that doesn't jump
I didn't associate any damage with them, but I got rid of them by putting all my pots under running tap water for a few minutes--this took a while but it was worth it. I have unchlorinated well water so I can do this. I read that springtails can be flushed from the medium this way--and it seemed to work for me. Even though they are probably not harmful, I didn't like having them around