Thanks to Mediha for telling me about this!
Grameen Foundation was created in 1997 to support the kind of work performed by Grameen Bank. Grameen Foundation then created Bankers without Borders to connect the intellectual capital of the private sector with Grameen's work via skills-based volunteer assignments.
These assignments can be on-site or remote, and can last anywhere from 2 weeks to four months, depending on the assignment.
Bankers without Borders is currently recruiting for these assignments.
Join the Bankers without Borders team here. Here's a great list of resources for potential volunteers.