A lot of places do shark dives. I've seen shark feedings in Nassau (Stuart Cove's Dive Bahamas) and in Fiji (aboard the Naia). While not a freediver myself, I doubt that either of these would be good for freediving with sharks.
In Nassau, we were advised to stay very still on a sandy bottom at 35' as Caribbean reef sharks came in for the food being distributed by the divemaster. They tried to keep this a very controlled environment so that it wouldn't get too dangerous. Having one or more freedivers coming down and popping up to the surface every minute wouldn't help that. However, it wasn't unusual to see a shark or two pass by on various reef dives in the area as well. So there's always the chance of seeing sharks elsewhere.
In Fiji, we watched blacktips while clinging to rocks in a fast-moving channel at about 50'. It was much more natural behavior from the sharks than in Nassau, but in a setting that I expect would be impossible for a freediver. And we didn't see any other requiem sharks while in Fiji.
I've seen various sharks that rest of the reef (nurse sharks in the Caribbean, white-tips in the Pacific) at numerous sites, and these would be viewable freediving. But I typically see a few in a week's scuba diving, so it's not a guaranteed thing.
-Mark