I just received a PCR member's email from IHG. Priority Club is the loyalty scheme for the Holiday Inn chain of hotels. You get points when you stay in their hotels - typically about 1000 per night, but there are promotions to get earn more points. You can use these to book stays in their hotels - either for 5000 points for a short list of hotels, or between 15,000 and 25,000 for a wider range of hotels. By signing up to this newsletter, it means that you can also earn points by shopping with your favourite high street and online retailers through Priority Club Shopping.
I also just found out from HKUD member "ahenry" that you can convert Virgin Flying Club points into Priority Club points, especially as Virgin points do expire if you haven't flown with them for a while!