Sharing music between IPhone and IPad

I have an IPhone 3G that is synched to one computer and an IPad First Gen that is synched to another computer. Is there any way to share the music between the two. When I plug the IPhone into the computer synched with the IPad, it only looks at the iOS and not any of the other content. The computer synched with the IPhone is in the US and the computer synched with the IPad is in Malaysia.