Are there any native tools for SVG conversion on OS X? How can I convert SVG image to something raster? Are there any native [command-line] tools on OS X that can do that? I am able to open them in Safari or Firefox, but doing "Save as..." only proposes original (.svg) or web-archive formats and no rasterized image format.
Try Gapplin. It works for me and creates PNG and JPG files from SVG. Simple and effective.

If you have a lot of SVG files to convert, ImageMagick is probably your best bet (available directly from imagemagick.org or via Homebrew).