Coalition to Increase Minority Degrees has a database of financial aid opportunities for undergraduate and graduate students who are studying science, math, and engineering.
Community of Science hosts an extensive database of funding opportunities that can be searched by a variety of criteria.
Fastweb Scholarships for Minorities - for undergraduates, graduate students, and postdoctoral fellows.
Grantsnet offers a database of research funding and scholarships for scientists at all levels.
The Harvard College Student Employment Office has a searchable database of funding sources for Harvard students pursuing research projects, as well as listings of undergraduate research opportunities.