Today I noticed a really annoying flaw in KDE3's Kopete - in the chat window, you have to use shortcuts like Ctrl+. to change to the next contact in the chat window instead of Ctrl+Tab that would be used in a similar situation in Firefox or other browsers. While this can be easily fixed in the configuration dialog, it reveals a greater problem: the general inconsistency of shortcuts where is no reason for it. I do agree that Emacs can't just adopt KDE's or Gnome's shortcuts. However, the shortcuts should be consistent where possible.
To ensure this, I would propose a new account-wide configuration file (to be placed e.g. in ~/.config). It would contain default application shortcuts, like "next tab" (e.g. Ctrl+Tab), "previous tab", "hide main window" (if applicable, as in case of amarok, kopete and kmail) etc. Though consistency is possible without a central storage file, it would enforce it.
I am aware that a new configuration file would further increase application startup time. However, if the shortcuts are customizable anyway, why not make them part of the common KDE environment? Only load them once and then transmit to all the KDE applications needing them. Not sure how you would manage changing them at the run time then, however.
Anyway, I think it would be great for people who only want to use their mice occasionally.