The ultimate compilation of statistical tables. Written for biologists, but with mathematical rigor. This is THE book for learning about multiple and logistic regression. JL Fleiss Statistical Methods for Rates and Proportions Relative risk, odds ratios, chi square, etc. The Art of Scientific Computing You absolutely need this if you write your own data analysis programs.
Editions are also available for Pascal and Fortran.
The writing is amazingly clear and fun. You can also download chapters as pdf files. HA Kahn CT Sempos Statistical Methods in Epidemiology Good explanation of logistic and proportional hazards regression. S Siegel N Castellan Nonparametric Statistics for the Behavioral Sciences Comprehensive cookbook of nonparametric statistics. Despite its title, very useful to biologists J Cohen Statistical Power Analysis for the Behavioral Sciences How to calculate sample size and power for many experimental designs.