Before I went to Hawaii, I was told that there was some sport climbing on the island but I don't recall exactly where. The rock was volcanic and was supposed to be very sharp so not a lot of people climb it. Unfortunately, the person that told me about it moved several years ago and I lost touch with her so I can't ask.
BTW, this should be in the Pacific Island forum, not General.
The only place near Waikiki where sport climbing is done is around Makapu'u, on the southeast corner of the island. Most of the rock here is new, crumbly, and 100% UNsafe, so i wouldn't venture out without a real good idea of an exact route. I've heard there is one company that does guided climbs at Makapu'u, and i've seen leftover evidence of them when hiking around the cliffs. Maybe a google search or chamber of commerce call could turn up their name, and they could give you an idea what is doable.