I love our 100s board. I paid a pretty penny for it from Insta-Learn, a local WA company, but I think it has been worth it. We've used it in so many ways, and I'm sure we will continue to do so. It comes with chips that correspond to each number. And each chip has a "key" or series of notches on the bottom that is unique. So it will only fit in its proper place.
Here you see us using the 100s board without the chips. We're using puffballs to practice our skip counting by 3s and 4s. It was a very helpful visual.
We also used some Montessori style bead chains to practice our skip counting.