Initial port of HexViewer for ST3 is at this branch https://github.com/facelessuser/HexViewer/tree/ST3
Report any bugs if they are found. May need to restart ST3 after installing. You may notice some hashes missing depending on your platform, this is more than likely because of the SSL version included with ST3's Python.
Currently check-summing doesn't work, but should be fixed soon. I will update when I have fixed this.
I no longer provide default keymaps with HexViewer, but I do provide an example keymap file.