E.B. White's Wikipedia entry.
An essay at the Books and Writers site dicussing E.B. White.
An NPR broadcast featuring E.B. White:
An extended and content rich essay from the BBC on E.B. White.
A collection of New York Times' articles about E.B. White, interviews, reviews, etc. from 1939 to 1994. You have to register to access (its free) but is probably worth doing so if only for the touching interview with him after the death of wife, Katherine, of 48 years.
A brief biographical essay on E.B. White in Through the Looking Glass Children's Book Review.