Credit cards for sure, I suppose many are international too so americans can easily get our money. It's the other way around that's tricky, setting up a SaaS from here and getting a payout. PayPal is here so they work with Brazilian banks. As for all the other payment processors, no luck. Though someone here linked to Intel's solution[1], which proxies through PayPal and seems like the way I'll go.

[1] http://software.intel.com/cloudservicesplatform/service/comm...