Zelig: I'm very glad you're on this ship with us.
Nice market action the last few days. I'm tossing a few litecoin into the LTC/UNO market on Bleutrade (don't usually hold LTC but I had some from selling another coin).
arby.pl is a great little tool - using just that and a few lines of your favorite script language you can talk to API's.
So it would require writing some lines of code that arby.pl references API data through then applies by talking back to the API. Something like "RDD/UNO:BID=RDD/BTC:BID*UNO/BTC:BID*0.95;changeIF{+/-5%}" (obviously it'd be more complex that than, just trying to grasp the basic concept). I suppose you'd also want it to size the orders relative to the orders on the other markets, and maybe place arbitraging trades after your order is filled.
The problem is that I know far too little (nothing) about coding to even have a 'favorite script language' & I spend about 80 hours a week in classes, working in a lab, or studying. Realistically, how many hours would it take me with "The idiots guide to: Python" to have an understanding adequate to create code like that?
Start here: https://www.python.org/about/gettingstarted/ Code academy also offers free courses if you can shoehorn it in your schedule. Python is a great way to get started - if you need a free shell to practice on I can hook you up.