"I like to follow the ponies. Unfortunately, my ponies like to follow the ponies too." -- Milton Berle
Horse race betting online is legal in certain US states.
I am registered with TVG and it allows for betting on 150 race tracks worldwide.
They also have a network on Directv.
If you are willing to do the homework required to handicap horses, or at least find "professionals" that have a successful track record (much like doing the fundamental and technical analysis required to do your own stock trading versus hiring a broker), then you can do fairly well.
Obviously its more than just picking consistent winners, its also about strategic wagering through the exotics.
Reference Andrew Beyer and Steven Davidowitz if you are a budding/curious horseplayer.
And no, dear chaps, I am not a track or OTB junkie. I enjoy researching some key horses and races and making the occasional bet from my pajamas.
I like Union Rags as the early futures favorite to win the 2012 Kentucky Derby.
Let it ride !