Math/CS. Just want to point out that the whole fellowship process seems...very random. I am a permanent resident so I could only apply to NSF, DOE and a few others (Hertz, Soros, and other CS-only). I had a first-round interview for Hertz, but didn't make it further. Rejected in all the others including NSF (not even an honorable mention). DOE CSGF was my last chance and somehow that worked! I applied with the exact same research plan, credentials, etc. to all of these.