Also, the OP asked about hydrocolloids, presumably to stabilize hollandaise. This seams like a no-brainer of an idea, but I haven't heard of anyone having good luck with it. I've added a bit of xanthan and couldn't discern any difference. So I looked through the literature, and found no recommendations for doing it, and one scientific paper that strongly recommends against it. It seems that chefs who stabilize just about everything else agree with the scientists.
The only counter example I've found is a derivative technique on the Ideas in Food site. It's more of spheriphication technique than a stabilizing one.
