There are different scholarships available for medical students from different sources. You can search for available scholarships here: http://www.scholarships.com/scholarship-search.aspx.

One of the most popular scholarships available is NUS scholarship which is available only for students who study at National University of Singapore (NUS).

Information on NUS scholarships is available here:
http://admissions.nus.edu.sg/financialaid.html.

Some of the other scholarships are:

Herbert W. Nickens Medical Student School Scholarships
http://www.aamc.org/about/awards/nickensscholarships.htm

Charles E. Culpeper Scholarships in Medical Science
http://www.goldmanpartnerships.org/Culpeper/CulpeperMedicalScholarInfo2005.htm