Whether for a rheumatic disease or not, anyone who is interested in participating is encouraged to volunteer online. Here are some places to consider:
ClinicalTrials.gov – This registry is run by the National Institutes of Health. It includes information on studies all over the world that are looking for participants.
ResearchMatch – This registry was developed by major academic institutions across the country. It was designed to connect scientists with people who may be a good match for their study.