Ok... this is NOT a scam. Good intro, huh? Bear with me.
It is a sports betting website... but it is legal in the US... and you can't lose ANY money... sound too good to be true? For once, it isn't, keep reading.
Really, the majority of your questions can be answered here (http://www.centsports.com/faq.php), but here is the basic idea: Congress passed a law making online gambling illegal. However, they didn't actually make the act of betting online illegal, they made the act of depositing money into an online gambling account illegal.
So, a bunch a kids from Texas A&M decided to come up with a way to circumvent this... CentSports. When you sign up, they give you $0.10. You can bet with it as you like. If you win, it is yours. If you lose (all the way back to $0.00), they deposit another $0.10 into your account. Unlimited dimes. Once you reach $20, you can cash out and they send you real money, a check in the mail.
How is this all possible you ask? It is ad sported. It displays ads on the website and also when you place a bet (unless you have Adblock of course). They make more from ad revenue than they pay out.
This is not a scam, you don't have to give out ANY personal information when you sign up. You give you name and email, no address, no phone number, no credit cards, bank info, any of that. I suppose if you reach $20 and cash out then they need an address to send the check to, but that is about it.
Still think it is a scam and/or illegal? Here is an article in Forbes about it:
If any of you do sign up, you should search for "Matt Jacobi" (me!) and add me as a friend!