I have a number of tracks that I have built, that i am willing to share. Please bear in mind, however, that most designs take 2 copies of the game (which I own, 'cause I wanted the 12 bikes).
Tracks I have built are:
Buenos Aires and Aldea Romana, Argentina / Adelaide, Albert Park, Eastern Creek and Phillip Island, Australia / A-1 Ring, Austria / Brno and Most, Czech Republic / Sakhir, Bahrain / Spa-Francorchamps and Zolder, Belgium / Caruaru, interlagos, Jacarepagua and Nelson Piquet, Brazil / Montreal, Mont Tremblant and Mosport Park, Canada / Shanghai, China / Dubai, Dubai / Aintree, Brands Hatch, Donnington Park and Silverstone, England / Albi, Charade, Flins les Mureaux, Magny-Cours, Paul Ricard and Val de Vienne, France / Hochenheim, Nurburgring and Sachsenring, Germany / Balatonring and Hungaroring, Hungary / Imola, Magione, and Monza, Italy / Fuji and TI Aida, Japan / Speang, malaysia / Hermanos Rodriguez, Mexico / Assen TT and Zandvoort, Holland / Kielce, Poland / Misano, San Marino / Bernova, Serbia / East london, Kyalami and Phakisa Freeway, South Africa / Albacete, Alcaniz, Jaram, Jerez and Valenciana, spain / Anderstorp, Sweden / istanbul, Turkey / Chaika, Ukraine / Barber Motorsports Park, Indianapolis, Lexington, Portland, Elkhart Lake, Sebring and Watkins Glen USA.
I use the game designs for Catalunya, Laguna Seca, Mugello and Motegi.
If you have a favorite track that I don't have, let me know - the only thing we can't easily do are crossovers or figure eights (like Suzuka)