You can deposit ven at Kraken.com and trade XBT/XVN (Bitcoin vs. Ven) there. I'm not sure if this is available in all us states, but if you have an address in Montana, New Mexico or South Carolina (the "no money transmitter license" required states) it should work, I think.
Venmo is an app for paying in dollars, it's not related to the Ven currency
In a brainstorming session, they came up with the “ven” from vendere, the Latin word for to sell, and “mo” from mobile.
http://www.businessweek.com/articles/2014-11-20/mobile-payment-startup-venmo-is-killing-cashIt's more like Apple Pay or TransferWise. I guess they have low costs because they process a high volume of transactions just like banks, without having to build the payment network like banks do. Using bitcoin could make these services cheaper, but it's not the low-hanging fruit. In the short term, they'll be competing with digital currency, and they're more efficient than banks, credit card companies or Western Union.
In related news, major Dutch banks recently announced they were looking in to how blockchain technology could make settlements between banks more efficient. Video in Dutch:
www.rtlnieuws.nl/economie/home/gaat-bitcoin-techniek-banken-helpen