A television series (Canadian I believe), about a stray German shepherd named "London", though I don't recall ever hearing it in the show. They generally just address him as "that dog", or something along those lines. It was also a movie in the 1960's or 50's, which was later adapted to a black and white series, and then later again, the colour version that still airs today on a couple networks.

The entire show is based around a dog that just keeps travelling, always wandering around helping the confused little human life. I remember watching it nearly daily for the longest time, for some reason.. it's really kind of terrible all in all. Not that the concept is that bad, it's kind of uplifting.. either way, it's not the greatest show ever but it used to seem so great to me when I was younger.

The theme song..

    "There's a voice that keeps on calling me.
    Down the road. That's where I'll always be.
    Oh, every stop I make, I make a new friend.
    Can't stay for long. Just turn around, and I'm gone again.
    Maybe tomorrow, I'll want to settle down.
    Until tomorrow, I'll just keep movin' on.
    So, if you want to join me for awhile,
    just grab your hat, and we'll travel light. That's hobo style.
    Maybe tomorrow, I'll want to settle down.
    Until tomorrow, I'll just keep movin' on.
    Until tomorrow, the whole world is my home."

There's a website with a bunch of other information, if you happen to be really interested:

http://www.members.tripod.com/kevinmccorrytv/hobo.html