Getting married.

For those of you that are married and had bridesmaids (or groomsmen), how did you go about asking them to be an attendant?  So far it all has been very casual - but reading some dumb girly articles they are saying I should have bought a gift and made a big to do about it. Oops. 

Did you have more than one maid of honor? I have a MOH already, but I'm meeting my sister in about an hour for lunch, and wanted to ask her to be my matron of honor alongside.  How did this work out for you?