The large, established maple tree in our front yard has developed black spots on its leaves. What is this? What can I do about it? Help.

The maple trees here in New York had those black spots for a couple years in a row. I asked the coperative extension and they said it was kind of fungus which ultimately should not harm the trees however, they also recommended not using the leaves in my compost.
Toadherder

That probably is "Black Tar Fungus" something maples have had for eons. Last year was a really good year for it and lots of people noticed the large spots, normally they are very small, and got worried and some places were selling "stuff" to spray that did no good except pollute the environment, and cost these people money. It isn't something you need to be really concerend about.

Yay! Thanks, guys! That's the best news I could have gotten.

It always amazes me how most people run out looking for something to spray the minute they notice something wrong with a plant.

Anyway, now I know to just leave it alone. Probably, it's like in humans--getting an occasional "cold" or other minor infection is good for the immune system, helps it cope when something bigger comes along.

So I'll consider it a good thing and move on.