As any API out there, SE API does need some kind of analytics support. I suspect the SO team has plans for something like this, though I haven't seen anything hinted at yet.

Here are some of the data points I'd like to see:

 - median number of unique IPs per day.
 - total number of unique IPs for a specific time period.
 - average number of API requests per day per unique IP for a specific time period.
 - number of API requests for the top N unique IPs per day for a specific time period.
 - % of unique IPs that hit the API limit (though ideally that one should be 0 :-))

As for data about individual IPs - that has some privacy implications and as an end user, I'd personally prefer if SO does not expose this information to the applications.

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**Edit:** Upon rereading the question, I realized that indeed that's not what @George is asking about. (Even without his update. :-))
However, I'll leave my original answer below to collect dust and downvotes, so that others don't make same mistake like me and lose precious rep.


Short version - you can see that information in the response HTTP headers:

> **X-RateLimit-Current:298**  
> **X-RateLimit-Max:300**  

More info in the answer of [Is there a way of querying how much of the API limit has been used?][1].


  [1]: http://stackapps.com/questions/71/is-there-a-way-of-querying-how-much-of-the-api-limit-has-been-used