Runtastic Mountain Bike Pro, a fully featured mountain biking application from the creators of the very well respected Runtastic running app, is free today only!
Normally priced at £4.29, the Pro version is activated by downloading the free version and entering a coupon code displayed in AppTurbo's AppOfTheDay app, a great little app which offers a new free title every day. I mentioned previously that often the free apps are pretty uninspiring (and i'm not sure they're always actually a deal), but that's two great titles inside a week now after the TNTBF2 deal.
One thing to note is that after the deal has passed, you're no won't be able to reactivate using the code if you uninstall / reset... so make sure you get a backup with your utility of choice (e.g. Titanium Backup) just to be safe! :)