Genome-wide CRISPR libraries: Brunello and Brie are available on Addgene, both as plasmid pools and virus.
sgRNA designer - This tool provides on-target scores for sgRNAs for use with CRISPR-Cas9 technology.
Please also see this blog post at Addgene for additional thoughts on sgRNA design. And really, check out all of Addgene! (John serves on the Advisory board for Addgene)
STARS - An analysis method that collapses information from multiple perturbations into a gene-level score. This tool is agnostic to the type of perturbation, RNAi or CRISPR.
Protocols - A list of GPP protocols for working with RNAi and CRISPR to perform genetic screens