Statistics 571: Statistical Methods
The Statistical Sleuth: A Course in the Methods of Data Analysis
by Fred L. Ramsey and Daniel W. Schafer. Duxbury. This is the best introductory statistics book that I have ever read. A great reference.
Sampling, Second Edition
by Steven K. Thompson. Wiley. A very complete treatment of sampling in standard and nonstandard contexts. Very pleasantly written.
Introduction to Linear Regression Analysis, Third Edition
by Douglas C. Montgomery, Elizabeth A. Peck, and G. Geoffrey Vining. Wiley. A very well-written introduction to regression including some modern methods.
Design and Analysis of Experiments, Fifth Edition
by Douglas C. Montgomery. Wiley. To me the most readable experimental design book.
An Introduction to Categorical Data Analysis
by Alan Agresti. Wiley. The baby classic work on categorical data analysis.
Applied Logistic Regression, Second Edition
by David W. Hosmer and Stanley Lemeshow. Wiley Interscience. A great introduction to logistic regression for those already familiar with the elements of multiple regression analysis.
Forecasting Principles and Applications
by Stephen A. DeLurgio. Inwin McGraw-Hill. A nicely written treatment of time series methods in the context of forecasting.