Funky Stevie Wonder

I just got "Songs in the Key of Life". I've never been a big fan of Stevie, but I guess it's cause I only knew his "radio" songs. But after listening to this album, well, I'm sure you've heard it before.
Anyway, I had no idea that Stevie Wonder could get so FUNKY!! I love the whole album (which covers a plethora of different styles) but I've become completely obsessed with "Sir Duke" which I'd only heard once or twice before and didn't even know who it was; and, even more so, the song "I Wish" (which I had never heard before yesterday). I need more of this ASAP. Can you guys recommend me some more Stevie Wonder songs or albums that follow the same upbeat super Funk feel as "I Wish"? All I can come up with off the top of my head is "Superstition" and "Higher Ground", again because those are the super-popular radio hits. What else is out there?

 

^Agreed, but I'm looking to put together a good compilation of his funky upbeat stuff (all done properly through iTunes and Rhapsody, I gave up illegal downloading after the second time it ruined my computer).
I fully intend to get a lot more of his music, but I am so completely in love with his funky upbeat stuff right now, that's all I'm looking for at the moment.