Ironically, Olympic hasn't got lines up yet. But they do have competitors listed that they will carry for Men's track, basketball, swimming, baseball, cycling & tennis, and Women's tennis, basketball & trialthlon.
One bet I may be looking for (though she may be the favorite when the odds come out, I am not sure) is Canada's Perdita Felicien in women's hurdles. She has been just murdering the competition leading up to the games. Looks to be at the peak of her craft right now & probably the best in the world. Just hoping the odds aren't too prohibitive.
(edit) Just noticed the Men's Baseball listing. Did the USA fail to qualify?? Canada and Cuba are the only teams listed from the Americas...wtf? Is the USA really not there??