From what I understand, counterspells work as follows: if someone casts a spell and you cast the same exact spell, the energies negate each other.
Assuming that's correct, I was wondering if there is such a thing as a wand that conjures any spell, provided it is used as a counterspell attack. It sounds kind of powerful--if it doesn't exist already, I would assume drawing up such a thing would put it in an artifact status more than just another magic item.
I don't have my books handy right now to see if such a thing has been published. :-) The thought just came to my mind.