I love this concept- we used to do something similar in our local pub on pen and paper and it really added something to the days punting. Definitely needed these days with affordability checks, so people who still want a small financial interest can without having to deal with bookies.
I know a few people who have taken part in similar things via twitter etc but always ends up a rigmarole trying to get people to cough up entry fees etc.
I will try and sign up if I get time.