General graduate school fellowships and honors in the sciences

• National Science Foundation Graduate Research Fellowship Program (NSF-GRFP)
• National Defense Science and Engineering Graduate Fellowship (NSDEG)
• Department of Energy – CSGF
• Hertz Fellowship
• Another large compilation of fellowships
• Fellowships for members of underrepresented groups 
• Lindau Nobel Laureate Meetings
• APS Prizes, Awards, and Dissertation Awards

For prospective Wash. U. students:

• Departmental and university funds

Other prestigious fellowships (descriptions directly copied or paraphrased from fellowshipsoffice.wustl.edu):

• Churchill Scholarship: Master’s degrees in STEM fields at the University of Cambridge.  Award: One-year award covers all tuition and fees, plus living, travel, and research allowances. Requires WU nomination.
• Gates Cambridge Scholarship: For study at the University of Cambridge. Award: 1-4 years of graduate study, including tuition and fees, twelve-month allowance, and round-trip airfare.
• Fulbright: Study, research, or teaching of English abroad. Award: One-year award, typically covering round-trip transportation, language or orientation courses, tuition, book and research allowances, and living expenses. Requires WU nominaton.
• Marshall scholarship: For study at any British university.  Award: Full tuition, fees, living allowance, and various expenses for 2-3 years. Requires WU nomination.
• Rhodes Scholarship: For study at Oxford University  Award: 2-3 years of full tuition, fees, living allowance, and travel expenses. Requires WU nomination.