Global custom fields, need help…

Heya,
I need to give my users the ability to edit areas of the website that are the same globally. For example, I have a header region with an address that appears the same on every page of my theme that the user needs to be able to edit. I’m looking for the best approach to accomplish this. Maybe an existing plugin, maybe a unique way of using custom fields, I’m really not sure. Just looking for some suggestions, thanks!