In a few months, GenoPro will have a solution for this. You will be able to save your family tree on the web and your relatives (or the people you invite) will be able to open the .gno file directly from the server. This feature will work transparently as if you are editing your .gno file locally, however there will be an internal mechanism to synchronize the .gno files (and its pictures). The pictures will be downloaded from the server to the local cache as necessary, and automatically updated when modified by someone else.
There is a bit of work to implement this feature regarding security and intelligent caching.
Check out a similar post "Pack it with pictures!".