I think it would be helpful for people who want to help if you mentioned about the kind of position you are applying for, but, generally speaking, I would encourage you to ask something you might have talked about during the course of the interview. That way, you don't appear too scripted and also shows that you can think for yourself. Of course, you will also have to do your own research about the company (industry..maybe?) and stuffs.

Also, rather than starting with, "what," "when," "why"...try to give it a context. For example, you could start with something like: I find it interesting....but why...? Also if the company is invoveld in multiple businesses, explore the connection between them (there has to be some..otheriwse the company wouldn't be in those businesses) and try to come up with some intriguing questions. Asking questions (of course with a context) about the impact of the current state of the economy to the business could be a good area as well.