Dashometer is an elegant and accurate GPS dashboard, speedometer, and navigation tool.
This App provides an easy to read -- and flexible -- display of GPS data. As a GPS dashboard/speedometer -style App it has somewhat unique features compared to similar Apps; these features include alarms, bookmarks, and the ability to export KML and GPX data.
Dashometer is consistently highly-rated, and is pretty frequently updated in response to customer feedback.
A video walk-through (of a slightly older version) is available here:
An iMovie trailer ;-)