If you already listen to the music of your iPhone while skating, you should get this! – iSkate - GPS skating computer for inline and roller skates Review

The app works as advertised with high accuracy (compared to my home skate track) and very stable for me! I use it with the Belkin Armband from the Apple online store and can even listen to my iPod music while I use the app. The best thing that I did not even dream about: Whatching my rides in Google Earth is so much fun... :-) Now I can show cool tracks to people that have not been there. This gets my full recommendation!
Review by iPhone Guru No 1 on iSkate - GPS skating computer for inline and roller skates.