If you are a Harvard undergraduate student interested in doing a research project (or a senior thesis) in Human-Computer Interaction (including topics like adaptive user interfaces, crowd-powered systems, accessibility, creativity, and more), please talk to me. I have a number of project ideas that you can contribute to, or you can propose your own. But take a look at the themes that run through my research to see what kinds of topics it would make sense for us to pursue together.
In general, the best time to join a research group is at the end of your sophomore year or at the beginning of your junior year. By that time, you should have enough technical background to contribute to a project, and still enough time left at Harvard to see the fruits of your labor. Ideal candidates would have taken at least one of CS 179, CS 171, CS 181, or CS 182. If you are a junior or senior and you are serious about pursuing research in HCI, I encourage you to take CS 279, a graduate class that will introduce you to the current research topics and the main research methods in HCI. The final project in CS 279 is often a great first step toward your own independent research project.
Below you can see examples of projects led by undergraduates (some were done as senior thesis, others just for fun) and projects where undergrads made significant contributions: