How to disable iTunes for one user
Under System Preferences >  Users &amp; Groups >  Login Items   Find iTunesHelper and remove it from the list of items that will open when you log in, this is the daemon that runs in the background checking for iOS devices connected.  

If you want to disable it for only one device instead of one user, connect the device, open iTunes and uncheck "Automatically sync when device is connected".

http://support.apple.com/kb/TS3927

For iPhoto I believe you can have another application open when connecting digital camera, not sure if it can be disabled.  Its a setting in iPhoto preferences, under General.

http://support.apple.com/kb/PH2500?viewlocale=en_US