Stack Exchange does have a combined reputation number and combined badge count, but it doesn't get you any privileges. It is only shown on your Stack Exchange flair image, that you can post somewhere if you want. Here is what my flair image looks like:
The Stack Exchange reputation number only includes reputation from sites where you have more than 200 reputation, so you don't yet have any Stack Exchange reputation. My Super User rep and badges are not included in this number currently, because I don't have 200 rep yet on this site.
