FollowMe allows you to record your GPS track and easily export it by e-mail to a variety of formats (CSV, GPX, KML, etc.). Several trips can be stored on your iPhone and managed independently.
Trips can then be imported in third-party tools to visualise them (like Google Earth).
No network connection is required during the recording, making it suitable in all environments, even when no 3G/GSM signal is available (especially useful when travelling abroad to avoid data roaming charges).
However, continued use of GPS running in the background can dramatically decrease battery life (on iOS 4).