See Freitag-Kiehl, original articles of Dwork and Deligne, and lots of printed stuff in my office.
Kiehl and Weissauer: Weil conj, perverse sheaves, etc
Katz and Messing: Some consequences of the Riemann hypothesis for varieties over finite fields (1974)
Mazur: Extremely readable survey
SBS concluding post: http://sbseminar.wordpress.com/2010/06/10/motive-ating-the-weil-conjecture-proof/
http://sbseminar.wordpress.com/2010/04/12/the-weil-conjectures-and-the-problem-of-coefficients/
http://sbseminar.wordpress.com/2010/04/19/the-weil-conjectures-curves/
Some early writings:
Irene had a book with some background.
The MathSciNet review of Deligne: La conjecture de Weil I, is very long and informative, with good historical references
nLab page on Weil conjectures