I've just spent some time refactoring GPSLog Labs so that it has much better support for logs in different timezones. For each log, you can specify the timezone that it was recorded in and it's times will be shown in that timezone no matter what your current timezone is set to, i.e. logs show the times you experience the activity.

The upshot of this is that if you were going for runs at 9am in one country, they'll appear at 9am when you compare them to runs in another country.