On your "homepage" at geocaching.com you can see (on the right side) how many favorite points you have remaining and how many you have been given to hand out (roughly number of caches divided by ten plus one). So it is a simple subtraction that gives you how many favorite points you have on caches you have found. Otherwise, you can always have a look at the "Favorite List" in your geocaching account:
http://www.geocaching.com/my/favorites.aspx.
I am not sure if this is possible at project-gc. I do not known whether the API has access to the My Favorite list. In principle it is a public bookmark list, so it should be possible to be checked easily.
(or did I completely misunderstood the question?)
