Well I've had several ideas brewing in my mind lately. The first of which, is: "How would Steve make a Lens?"
Well, my answer to that is... The Buffer pad. Recipe in spoiler below.
This would give Steve a way to take glass and make it clear enough to focus light through. But how would he use this pad you ask? Simple, attach it to a turntable! This gives it the rotation and speed to easily allow Steve to polish that lens to light-focusing perfection.
My next thought was that since we already have a compass and redstone as a power source. Why not combine to the two to amplify the magnetic field sensing properties of said compass. And thus, the handheld metal detector is formed! Recipe in spoiler.
This device would allow Steve to detect iron, and gold ores from 10-15 blocks away. It does not tell you the vertical height of the ore though, only a general direction (better than blindly digging in my opinion).
And lastly, doesn't rain breaking your windmills annoy you? I present to you the Rainproof sail! Recipe below.
Since we now have tallow, why not coat our sails with it and keep them nice and dry. This could either be a recipe as I've shown to be crafted, or put all the materials into a cauldron and then tallow is melted right into the cloth (making a better bond).