This is a good beginners' guide for those who are interested in trading bitcoin: http://www.reddit.com/r/BitcoinMark...eginners_guide_to_margin_trading_on_bitfinex/ "There are 3 options to choose from on Bitfinex; Exchange, Margin Trade, and Liquidity Swaps. If you head to their 'how it works' page (https://www.bitfinex.com/pages/howitworks), you'll be able to find a good explaination of each of the 3 different functions available." I won't copy the whole post, also read the discussion for more clarity...
Apparently, you can make 87% APY on Bitfinex, by lending out your money for margin users. The risk is that you might lose it all in case of a crash... http://www.reddit.com/r/BitcoinMark...sks_associated_with_moving_a_large_amount_of/