Ripple is a fairly new platform for instantaneous, p2p money transfers. Ripple has it's own currency - XRP, which we won't be interested in, here. We are interested in other currencies, which Ripple enables to trade, USD and EUR in particular, because we accept them as collateral.
In fact, on Ripple, you don't trade USD and EUR directly, but you trade with someone's debt denominated in these currencies (cf. IOU). In other words, such an entity is an issuer of that currency. We trust two such issuers, major players in Bitcoin and Ripple ecosystems: Bitstamp and The Rock gateways and we accept USD and EUR issued by them as collateral.
So, how would you send us collateral using Ripple and these issuers? You must have accounts in Ripple and one of these issuers, say Bitstamp for example. First, you send some amount of USD to Bitstamp (either by bank transfer, or exchange BTC). Then you send these USD to your Ripple account (you have to trust Bitstamp in Ripple to do so). So, now you have, so called, BitstampUSD - USD issued by Bitstamp - in your Ripple wallet. Now, you can send these USD to us as collateral, because we also trust Bitstamp.
Bitstamp supports USD, The Rock supports both USD and EUR. Bitstamp requires more formalities to make an account usable, The Rock requires nearly no formalities. We have found both reliable.
Opening Ripple account is easy, please refer to it's website or wiki (although, if you have any problems, we may help). The only issue you may have at the beginning, is that you are required to have 25 XRP to be able to start really using it - please contact us if you want to open the account to trade with us; we will send you the required amount of XRP.
