As far as I know there are not any other Craig Thomas sites out there, but here are a few of interest.
Conor's site with a 3DSM mesh model of the MiG-31: www.plaything.co.uk/cgorman
Naomi's Unofficial Japanese page.
Chris Moore's official page. Chris had provided cover art for nearly all of Craig's novels in the 1980s and 1990s.
Craig Thomas/Firefox Pages
Most relevant is Kurt's well-designed Firefox page which can be found here. You can contact him at his email address: email@example.com. If you're interested in a high resolution, 99% accurate full-colour poster illustration of the plane, send him an email and he'll notify you as soon as he's done and ready to take orders.
My second favourite author after Craig is Gerald Seymour. I have my own page Gerald Seymour, the art of danger.Model Kits
And finally www.cometminiatures.co.uk offer a couple of Firefox model kits.