Why would I know?

i vote for xbet.io 5/5

funds in escrow quick payouts

You need to specify the -rpcport of the instance you want to stop (probably 7332).

For the first time it is now possible to perform Bitcoin-based betting in a decentralized fashion, meaning without the need of entrusting your funds in the hands of a third party – all wagers made using our application are held in escrow by a smart contract until the bet is settled.

edit: details on affiliate program and it's bounty are at the end of the ANN text.

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Among the benefits:
Secrecy:
Users have complete anonymity when using our services.
 
Security:
Users' funds are kept safe at the protocol level – thanks to the use of Bitcoin 2.0 technologies, the users are not required to transfer their coins into the custody of any application, and there is no centralized party that holds and manages users funds (no Mt.gox etc').
 
Transparency:
Because the application works using the Bitcoin Blockchain, all of its actions are visible to anyone and can be retraced by anyone with great ease.
 
Reliability:
The Counterparty protocol, which is the Bitcoin 2.0 protocol in which XBet.IO is implemented, is based on secured Bitcoin transactions, thus utilizes the Bitcoin network's highly secured and dependable features.
 
General Bitcoin benefits:
The use of Bitcoins holds numerous advantages over fiat currency (such as $, €, etc') - anonymity, independence, no inflation, cryptographic security, instant payments for any amount, and much more. Up until now, Bitcoin did not reach its full potential in existing large scale thriving industries, in which its special attributes gives it a distinctive edge and especially in the field of sport bets. The existence of a distributed and cryptographically secured system in which the operators of a betting application, or anyone else for that matter, have no ability to take / confiscate users funds, but can only decide which one of the participants is the winner of the pot is what distinguishes the XBet.IO application from any and all other sport betting websites, whether Bitcoin-based or Fiat-based. Introducing the sport bets industry into the world of Bitcoin can elevate the Bitcoin economy to great new heights.
 
Better odds:
For any wager, there is a counter wager, commonly referred to as 'The House wager' or 'Lay'. In old fashioned betting websites and casinos, the user bets against the house in the fixed unattractive odds determined by the 'House', and so the 'House' gains if and when the user looses. The XBet.IO application synchronizes users' bets and allows users to choose their own odds and bet directly between users. There is no middleman, thus all arbitrage revenue is there for the users to profit.
* In order to kickstart the application, counter wagers will be made on behalf of the XBet.IO application for bets that are- a. within the odds presented by the website as a non-organic odds (organic, meaning that a verified bet has been placed by a user); b. in lines where no odds-attractive, organic bets exist. This mechanism was set in place for a double purpose – both to allow users to know the real world odds for their wager and to ensure that the first attractive betters of every line will always have their offers matched for at least a portion of their wager.

 
What wagers can I make?
http://i.imgur.com/l798JEn.png

How many times did you get to see a match and said to yourselves "I don't know who will win, but I know there will not be a tie"? In the XBet.IO application you can choose to wager on the option that you think will happen and also for the opposite option, meaning everything but the specified result. For the aforementioned case, it is possible to place a bet that will award you with the pot in case of a draw (placing this kind of bet is called 'back', meaning that you are 'backing' the possibility of a draw),  or alternatively, you could place a bet that will award you with the pot in all cases except the draw, which means that it does not matter which team wins, as long as the result is not a draw, you will take the pot (placing this kind of bet is called 'lay', meaning that you are 'laying' an opposition to the possibility of a draw).
The XBet.IO application currently receives matches from all the major soccer and basketball leagues, including the 2014 world cup in Brazil. At this time the XBet.IO application analyzes results from over 200 different leagues from dozens of countries.
During the summer, the main event will be the 2014 world cup in Brazil, and the NBA finals.
Incorporating additional lines, sports and countries is already in play.
 
How to make a bet?
Check out this one minute tutorial and you will be good to go:
https://xbet.io/how_to_bet
1.       Browse through the various lines available on the XBet.IO application until you find one that you want your make your bet on.
2.       Insert the details of the bet that you want to make (your betting address, wager amount and your desired odds. All other details are preconfigured to match the bet type which you have selected).
3.       Paste the bet code in your account at Counterwallet.co and hit send.
Done!
Your bet has now been placed and can be matched by other users from the Bitcoin network.
 
Since the XBet.IO application is based on the Bitcoin blockchain, and implemented using the Counterparty protocol, in order to use it, one must acquire some Bitcoins and as many XCP as one would like to place as wagers. All wagers, counter wagers and pots are denominated in the form of XCP, which is the native currency of the Counterparty protocol. It is possible to acquire XCP through a traditional exchange service, such as BTER.COM or, and it could also be purchased using Counterparty's built-in decentralized exchange.
Placing bets, buy/sell orders on the decentralized exchange, and many other options are made easy through a free service called Counterwallet- a user friendly online wallet, built by the Counterparty protocol original developers.
 
Some of our future plans:
1.       Incorporating additional sports, starting with tennis and horse racing.
2.       Incorporating global events.
3.       Expanding the betting possibilities for each single event.
4.       Binary options.
5.       Issuance of the XBet.IO application on top of the Counterparty protocol.


What is new since the PRE ANN?
As you might have noticed, a test version on testnet was publicly available since may under the name CounterSports.com. Since then, we have made the following enhancements:
Improved UI.
Integrated fully with Counterwallet.
Added the NBA finals and other basketball leagues.
Changed domain, logo and branding.
Completed intense testing on the application.

Live on XBet.IO

Affiliates Program
We are proud to announce the XBet.IO affiliate program.

If you too are excited by Bitcoin, Bitcoin 2.0 technology and the promise it entails, come and earn some money of it.
As affiliates in XBet.IO's affiliate program, you will receive 20% of the fees collected by XBet.IO from users referred by you. For life!
For additional details and signup, press here.

A bounty for 100 XCP will be given to the highest rated affiliate at the end of the world cup!
A bounty for 50 XCP will be given to the 2nd highest rated affiliate at the end of the world cup!
A bounty for 10 XCP will be given to the 3rd highest rated affiliate at the end of the world cup!

edit:
Place your bet using Counterwallet - https://counterwallet.co

What does the press has to say?

http://www.bestbitcoincasino.com/xbet-io-enables-sports-bets-using-blockchain-and-counterparty-xcp/


Users' content
http://jpja.net/2014/06/counterparty-adds-betting-to-bitcoin/
http://knircky.blogspot.com/2014/06/peer-to-peer-sportsbetting-in-5-steps.html
Reddit : http://www.reddit.com/r/Bitcoin/comments/27u0u7/peer2peer_betting_with_bitcoincounterparty/
Added chinese language support (credit goes to amy_bit)-
counterparty中国志愿者论坛出品：如何使用xcp参与bet
http://8btc.com/forum.php?mod=viewthread&tid=5750&page=1&extra=#pid16181