The best for Arbing I find is www.zeroriskbets.com
they come in the form of an email and are really good for things like Formula one arbs. There are loads of Eurovulsion Song contest ones at the moment. But I find they offer decent arbs and have had no palpable errors with these yet. This is the format of the email very easy to understand.
Eurovision : Top Ten Finish (4.218%)
Albania Top Ten 15.00 Sportingbet
BET = 69
Albania Not Top Ten 1.120 Bwin
BET = 931
GUARANTEED PROFIT: 4.218%
I find as long as I get on within 2-3 hours of the email being sent to me I can usually get the odds on offer. They only use A1 bookies and as such you can usually place big arbs fairly easily. The only real downside is some arbs are a long way in the future. For instance before the Formula 1 season started there were 12-20% arbs based on the final standings at the end of the season. Sadly I had to ignore these as I can't tie up my capital for 6 months. The most I will do is 1 week in advance and I find there is usually 40-50 a week that fall into this category.
The other main one I use is 100percentwinners.com this is a lot more expensive and there are a lot of palpable errors some of the arbs can show 60-80% profit these ones can be very dodgy. And normally one bookie will cancel your bet on these high %'age ones.
I have however got a 55% Arb completed but one of the bookies would only take £45 Max stake and as I'd already staked £500 with the opposing bookie I had to lay a lot of it off. I managed to turn my lay into a profit, so even these aren't that cut and dried. They use many obscur bookies and sports books sometimes you have to factor in Currency changes in the price as they might only use USD or Eur. Also some of the Sportsbooks word things in a different way and it's easy to put things on the wrong event and often the price is gone. Sometimes the Arb appears and the event has already been cancelled on their books.
If you do either of these services then I think Zerorisk bets should be the one there are less arbs approx 100 per week but how many people can get on many more with their bank rolls to make a decent income from it?
I have a number of other services I am trying at the moment I'll report on them when I get a chance.