Settings for w3m's urimethodmap. It allows you to define custom uri schemes and map them to scripts. Scripts must be in the directory defined in programs.w3m.settings.cgi_bin.
As of w3m v0.5.5, urimethodmap doesn't respect the W3M_DIR environment variable, so unless programs.w3m.settings.urimethodmap is set, urimethodmap will always be at ~/.w3m/urimethodmap.