GNU R interface to genome browsers and their annotation tracks

 Extensible framework for interacting with multiple genome browsers
 (currently UCSC built-in) and manipulating annotation tracks in various
 formats (currently GFF, BED, bedGraph, BED15, WIG, BigWig and 2bit
 built-in). The user may export/import tracks to/from the supported
 browsers, as well as query and modify the browser state, such as the
 current viewport.