So I think I'm mostly trying to get DNN to do something that Sitecore does well, that DNN just doesn't have.

For the above, I am looking for a Global resource, not one for just MySkin or MyTheme. I wanted this to be shared across every .ascx / skin in the theme (and, kind of along the entire solution). I have tried several ways to access this via Localization.GetString(), but not sure what the second parameter should be.

I created {theme}/App_LocalResources/SharedResources.resx, however things like:

Localization.GetString("foo", Server.MapPath(PortalSettings.ActiveTab.SkinPath + "App_LocalResources/SharedResources.resx"));
Localization.GetString("foo", PortalSettings.ActiveTab.SkinPath + "App_LocalResources/SharedResources.resx");

And everything else I've tried to date has yielded a NULL.

I know you've talked about this on other threads, but still coming up empty.