NPD, has posted the Top 5 titles for consoles up until August. Don't expect any surprises: Grand Theft Auto IV is in the top spot for PS3 and Xbox 360, while Super Smash Bros. Brawl is champion on the Wii.
The Wii certainly is the most interesting of the lists, with four out of the five SKUs belonging to games with included with some sort of peripheral (Mario Kart, Wii Fit, Wii Play and Guitar Hero III). Gamasutra also estimates that the software sales of the top five Wii titles combined is about 12 million units, nearly double that of the top five on the other consoles (separately). Of course, the year isn't over yet.