It sounds like your DD is a lot like Darth Jayden - very much into building and learning.

Our kiddo loved the "Gears! Gears! Gears!" toys. I bought the first box for $.50 at a yard sale, and that turned him on to the idea. Later, we got him a bigger set, both a big hit.
http://www.amazon.com/Gears-Super-Set-150-Piece/dp/B00000JGW...

Also, if you want to do stealth learning, go for one of those snap electronics kits. Again, it sounds like just the ticket for a curious, engineery-type mind.
http://www.amazon.com/Elenco-SC-300-Snap-Circuits/dp/B000068...

Telescopes are always good for learning, as is a microscope, which has the added bonus of being able to turn into a family outing. As in, walk around the neighborhood and "Ooh, I wonder what THIS will look like?" <gather specimen>

We really enjoyed The Ladybug Game, though it's pretty simple for that age - probably more appropriate for a child just learning to count to 10.

If you're into computer / video games, I can add a lot more.