Being able to upload songs is especially vital when recording outside of the studio. Cloud services have made this incredibly easy. I typically use two of these services; both are completely free.
These are both pretty standard apps; I'm sure you can find detailed reviews online if you want to know more.
1. Transferring files between devices: Dropbox
2. Uploading songs to the masses: Soundcloud
The cross-platform compatibility of these apps, makes them perfect for this project. There may be many alternatives, but I've never had a reason to stray.