Yes, it is perfectly possible, and appropriate to create pages on behalf of an organisation (or brand or product for that matter). It's very rare that a client will be able to manage their online presence, especially if they are none-technical : that's the reason why they employ marketing agencies after all.
Create the page via http://www.facebook.com/#!/pages/manage/ - be aware that in order to set the "pretty url" (e.g. faceboom.com/my-charity), the page needs to have a minimum number of people "connected to it" (fans). Currently this figure is 25.
After the page it set up, you can add additional Admin users to allow them to control / edit the page. I guess you should therefore be able to transfer ownership by adding the new owner, and then removing yourself (though I haven't tried this so I can't confirm).