That's not usually how it works. You tell an SP what you want, and she does it (asuming that you are not boundary pushing). It is rare for an SP to ask for something that you have not requested yourself, although I have had it a couple of times, and maybe regulars are different. However, assuming that you are interested in things that we punters really don't want in a meeting, and wouldn't request, then here the ones that come to me off the top of my head.
1. Hardsports as you mention; probably a very limited market. Watersports I have tried both ways on a few occasions, and they don't do anything for me, even without the added pressure of performaning where I have failed once and also had an SP fail twice. I might be persuaded in a femdom situation where it maintained the flow (so to speak).
2. Pain. I enjoy a light spanking by hand or implement, but all symbolic in a roleplay and no real pain involved. I am too much of a wimp to receive, but also don't like hurting people, so even giving is pretty mild.
3. Receiving anal. This is an odd one. In theory, I find this very erotic, but in practice it does nothing for me, and I can't be bothered with all the douching preparation. I have had a number of SPs try with fingers or toys and I am just bored until we move on to something else. After rimming a woman (I love this), she will sometimes offer to return the favour; it seems churlish to say no, especially if it's not on her likes list, but really I could do without.
4. Bareback; probably goes without saying.
Otherwise, I am usually up for anything, especially if it "perverted" or unusual. It's great when an SP includes on her profile activities that she enjoys or specialises in to help generate ideas on my part.
