and genetic/individual differences in processing:
http://www.pharmgkb.org/
Their Mission: To collect, encode, and disseminate knowledge about the impact of human genetic variations on drug response. We curate primary genotype and phenotype data, annotate gene variants and gene-drug-disease relationships via literature review, and summarize important PGx genes and drug pathways.
Another interesting site: http://www.pgxlab.com/general_public/