power and sample size programs

Biostatistics Uni UCSF
list of statistical programs for different types of analyses - extensive

on estimation of power/ss for logistic regression in stata from UCLA

site - but rather simple calculations //by eugene demidenko //cf author of recent book on Mixed models

site2 - logistic regression with covariate with measurement ERROR, generalized linear models etc - ALSO GIVES PLOTS OF POWER, OR, SAMPLE SIZE