Some Useful Mathematical Tables  
   A collection of mathematical tables which, for some reason, have not been published elsewhere.
   http://www.maths.soton.ac.uk/staff/Dewynne/mathtables.html

Tables of Mathematical Constants  
   A list of known constants with a precision of 16 digits.
   http://pi.lacim.uqam.ca/eng/table_en.html

A Million Random Digits with 100,000 Normal Deviates  
   Free online in PDF, also offered for sale as paperback. Notes on the data and instructions for accessing the files in either plain text or compressed format are provided.
   http://www.rand.org/publications/MR/MR1418/index.html

Dave's Math Tables  
   Has math tables for many areas of math from general math to advanced calculus. Includes areas formulas and integral approximation formulas.
   http://www.math2.org/