If you want editors to be able to manage these values you can create a content only page type with a few fields in it. For instance, SettingType, SettingTitle, SettingValue. Type could be a list of whatever values you want but allow you to draw them out using a query like
WHERE SettingType = 'clients'
Then place those "pages" under a folder called "settings" in the content tree. This will allow the content editors to edit them as needed.
We've also setup custom tables to handle things like this but found it to be easier to work with the content only page type.