Navigon has dropped the price of MobileNavigator North America (iTunes link) by $20 to $69.99 as part of a Thanksgiving special (was $89.99). The discounted price lasts until November 30, 2009. They are also offering a $10 discount on their Live Traffic feature (purchased in-app), which normally goes for $24.99 but now costs $14.99.
We recently published our Guide to iPhone GPS Apps and found Navigon to be the best reviewed of all iPhone GPS apps.