Sir, You Are Being Hunted lead programmer Tom Betts has cooked up a procedurally-generated racer called Permutation Racer.
Available for free from Sir, You Are Being Hunted developer Big Robot's site, Permutation Racer is a free prototype Betts wrapped up over the holiday.
It's pretty simple: you race against the clock through a randomised landscape while collecting stars, avoiding spikes, and hitting checkpoints. It bears a passing resemblance to Race the Sun, and while it may not be as polished as Flippfly's arcade racer, it's also free and has some pretty slick audio. Check it out.