Many students become interested in biomedical engineering by way of prostheses. Creating prostheses is only a small part of what biomedical engineers do, but I think is appealing because the need is obvious and the devices are relatively easy to understand. Here is a link to a low cost prosthetic hand that has been developed in part in South Africa: (if you're impatient, start about 4 minutes into the video). I first heard about it while visiting an MSOE BE program alumnus there.