Unfortunalety I'm not very good at JS/HTML. I did create some easy program, but it was a long time ago. I may have JS at school on IT next year, I'll try to convince my teacher to do JS extensively. (Palm Pre apps are still waiting to be run on N900 )

Me and TransTech are looking for some people who are good at JS as we don't know it well.

I've got an idea anyway, a conception.
An approximate direction against the road you're running. If you're not perfectly on the road, but you're in the direction it's a good situation and ovi maps talks then.

if you get away from the road and get back (e.g. parking) the direction is preserved and it's still the opportunity for the voice guide to be spoken.

Guide'd be spoken relatively to the direction