Whatever you feel will best prove to us that you are capable of producing great software. What does this mean?
future developers will enjoy maintaining your work
your work meets requirements for the project
you are capable of completing the project iteratively
Should I include references?
Yes, this is a good idea. You're applying for a job. A good reference, for example, might be a professor you worked well with or a mentor from a past GSoC. Expect that we will follow up with at least one reference.
Must I build Mifos before applying?
No. While developing Mifos, you will be required to build the software regularly. If you are able to follow our directions and build Mifos, that will bolster our confidence in your ability to work effectively on Mifos.
I've built Mifos, I've applied, I've done everything I can think of. What more could I do to improve my chances of being accepted?