Search these websites for listings of internships, experiential learning opportunities, academic fellowships and scholarships funded by government and private sector organizations:
East Asia & Pacific Summer Research (NSF EAPSI)-$5,000 stipend plus airfare; partner institutions pay living expenses. Deadline in November
Indeed.com-searchable by keyword and location
Internships.com-searchable by keyword and location--some are virtual
Medzilla.com- healthcare, pharma, biotech, science
FindInternships.com -also has interesting articles and tips
If you are interested in larger industry, see also this BEST page for internship opportunities.