Upvote:6
If you're in the UK, you can subscribe to Railmiles. It is primarily aimed at the UK as it will automatically fill in details like the operator, train ID, stock allocation (where available), booked and actual departure and arrival times, etc., using data from Realtime Trains. It does let you enter journeys for abroad though; there's nothing stopping you entering whatever you want. You can see my page here.
Conflict of interest statement: I am friends with the guy who runs this website, though I'm completely sure that I would be using the site even if I weren't friends with him :)