The bot checks for altcoins, which are traded on both Poloniex and Bittrex and compares their prices. If the difference is big enough to earn at least some satoshis (after deducting transfer fees), it enters the trade. The bot records its activities and exchange rates in a database and uses this information to reinvest a portion of its profits into the most profitable (in terms of arbitragable) altcoin. Additionally, the amount of held altcoins is calculated based on their exchange rate. This allows the bot to profit from hyped (PnD) coins. You can see the bot running on a $5 Digital Ocean VPS here: http://178.17.174.178/
Screenshot:
GitHub link: https://github.com/opencryptotrader/arbbot
Feedback & contributions are highly appreciated.