I recently opened an account at a credit union here, which includes a checking account. They gave me a book of checks on the spot.
Are they valid and usable? They simply came out of the drawer and don't have my name on it or anything.
Checks like these are called starter checks. You are meant to use them until you have time to order real checks.
They are completely valid. You should have no trouble using them for paying your monthly bills, as utility companies and the like do not hand process payments. Their computers scan the banking information and read the payment amount entered in the numeric display.
As far as I know, there is no legal standard for a check. It is in effect just an IOU in the standard form that a bank will pay out for you. If you can get a merchant to accept it and your bank to honor it you could write a note on a napkin that says:
I authorize my bank to pay merchantABC $500 from my account.
(Your Signature and the current date)
Some funny stories about weird checks in this Straight Dope article: Can you write a check on any old piece of paper?