My plans are to continue developing API libraries for CI in my free time. One thing I am going to do is combine the YouTube and Dropbox libraries into the same github repo since they do share some common code in oauth_helper. That would mean only having to update things in one place as opposed to several in the current repo structure.
That being said, I am starting to run out of decent API ideas. I think the next one I will tackle is the NetFlix API but beyond that I am really not sure.
What API libraries would you like to see implemented in CodeIgniter?