Remember, this one remains to be completely solved:
Every day on his way to work a man passes by a small building, and chuckles when he sees it. The reason he thinks it's mildly amusing is that it makes a type of product, but can't use that product itself. It's a product that each and every one of you has almost certainly used before, some of you every day, and many buildings use it. What is the product that the company sells, but can't use it in its own building? Technically it can use it, but it would be strange and wasteful to do so.
I edited it a little, and I can think of three right answers.
Every day on his way to work a man passes by a small building, and chuckles when he sees it. The reason he thinks it's mildly amusing is that it makes a type of product, but can't use that product itself. It's a product that each and every one of you has almost certainly used before, some of you every day, and many buildings use it. What is the product that the company sells, but can't use it in its own building? Technically it can use it, but it would be strange and wasteful to do so.
I edited it a little, and I can think of three right answers.
Yes, as a matter of fact, they do! 
I was about to say, "The key is the 13th word of the riddle; if the building were not this, its product would be much more useful to itself," but you already got it right. Now, I've decided that one of the answers I was thinking of doesn't work, so there is still one possible correct answer left.
