When I remember to take it, I take this Calcium + supplement by Rainbow Light. It's got calcium, magnesium, vitamin D, and a number of good joint supportive herbs.

I often forget to take it because I have to take it separately from my iron pills because it interferes with iron absorption. I always remember my iron first thing in the morning, but then have to wait 6 more hours before I can take the calcium. And by then my day gets so busy that I forget.