The obvious thing to do is cook up the spaghetti and sauce it, and this I did. Got some Ragu Homestyle meat sauce, which worked nicely.
Seems kind of silly to cook less than half a pound of the spaghetti at a time, so I had basically an entire day of eating nothing else. Wouldn't do it every day, but it's fine as a change of pace. Probably get some meatballs to add in next time, too.
The other half-pound of spaghetti from that box went toward trying out spaghetti au gratin. The recipe was on the box, so I figured I'd give it a shot. It contains large amounts of pasta and cheese, which is highly relevant to my interests. Took about an hour of preparation and cooking time.The pan I had available was a little larger than recommended, so the result was thinner and crunchier than I'd like. Nothing wrong with the taste, though. Just fine when refrigerated and then warmed up, too, which is important since that pan is about 2 days worth of food for me. Not bad for a first attempt.
All that, and I still have another box of spaghetti to use up. Think I'll wait a couple of weeks before doing something like this again. Much as I like my pasta, several days of basically nothing but spaghetti is a bit of an overload.