Samscope is a lightweight SAM/BAM file viewer that makes visually exploring next generation sequencing data as intuitive as Google Maps. Samscope uses multiple layers to simultaneously (or sequentially) view SAM/BAM related features like coverage or allele frequency, or ChIP-SEQ features like polarity from as many files as you like. The paging-friendly binary file layout makes it feasible to browse data sets far larger than the system's available RAM.