Zack, I absolutely flipping love you right now <3
I still remember my Apple IIe days playing Math Muncher and Oregon Trail in the computer lab on those incredibly-rare days that we'd be able to use it. In joining my school's computer club, it was just a way to use the computers more than once every other month lol. Kinda sad that the computer lab would go unused for days at a time because teachers didn't feel like using it. :(
I have to say that video games have had the single greatest impact on my life when it comes to learning things through tangential learning. I would say that I could assist you in coming up with several dozen bits of tangential learning opportunities (with full lesson plans) but I'd need to of course get paid for that. Not sure if your school's budget permits hiring a consultant ;)
Here's some freebies though:
-Many turn-based 8-bit and 16-bit RPGs in general are typically excellent for vocabulary, grammar, and syntax of the English language. Check out the Final Fantasy series. Not perfect but still nice. I'd highly recommend Final Fantasy 6 in particular. An entire curriculum could be drawn around the various themes of the game, the characters, the world design, the philosophy of the human condition, the ethics of theft/vandalism against an oppressive totalitiarian force (think 1984 but interactive) and dozens of other topics.
-I learned the word 'anasthetic' from Ninja Gaiden 1 for NES. Please don't completely discount a game just because of genre or the type of game it is.
-Final advice: Nearly any (good) game can be a learning opportunity. Some classic examples are the 'Civilization' series of games. There's a FLOSS (Free and Libre Open Source Software) clone called 'FreeCiv' which would be excellent for the classroom IMHO.