Most residents and PD's I've talked to seem to think that any research is fine, and if it's pertinent, it's just an added bonus. Brownie points also given for demonstration of long-term interest/involvement (e.g. getting a poster and an article for one project, as opposed to 5 "experiences" with nothing to show).
The best way to get started is to cold-call local research facilities + contact many faculty members at your school who are either teaching in your subject of interest or are known to be doing research.
It's by far much easier to join an existing project. However, it's all the better if you have an idea of what you might like to do when you come to these people.