I want basically the same thing and I haven't been able to find anything. Like you, all I can find are apps that use the gps. I don't take my phone with me when I'm out exercising, so I just want a log.
This app has been proposed to user kyleg, who was looking for app ideas.
App Ideas
Currently, I am using the Gdocs Notepad app on my Droid to write down the info (date, activity, mileage, time). Gdocs Notepad will synchronize with Google Docs. I then pull it up on my computer and transfer the info to a spreadsheet in Google Docs. Lot of hassle, but it works until someone develops an app that does this for me.