If you know where (at least the state) she went to school, there is a chance that she will be listed on classmates.com .
Create an account, and do a search. If they are there you can search by married name, and you'll see the maiden name.
You may not want to use your real email address, as I believe they will send you all kinds of spam. You can create a disposable email address at one of the places listed at http://email.about.com/cs/dispaddrre...disposable.htm
(I use spamgourmet.com)
That way, when the spam rolls in, you can just delete the address.
Hope that this helps.