Dropbox

That is a good question that I don't have a really good answer to (not being an iPad user), but what I usually do is select the print option (here on Chordie) and choose "print to file" from my printer option menu.  I then can save a copy of the tune to my local drive in pdf format that I can do whatever I want with (including sending a copy to the "cloud").  It's really convenient to have the music stored locally for me, as I can sort or choose selections for specific set-lists and still get all that with or without web access, as long as the batteries last.