Oh man...there are hundreds of american companies which sponsor H1Bs. As long as you are good (better than fellow americans) , big American companies will be delighted to have you.  Sponsoring is not a big deal for such big companies. The only problem that has been plaguing the market recently has been the limited quota. So, its not a guarantee that you will get a H1B. This is one of the reasons why smaller companies are unwilling to sponsor H1B. They do not want to spend on your training and sponsorship because they aren't sure if you will get to work for them next year.

 First of all, find an area of your interest. I don't know what was your focus in MBA  as the curriculum  varies across universities but if you are interested in financial consulting or even economic, strategic consulting, google it and you will find hundreds of really good companies. A few names that come to my mind right now: Cornerstone, Lexecon, CRA, Analysis group,, NERA, LECG etc...These aren't that big but they all sponsor H1Bs.

By the way, did you also intern anywhere during your MBA process?  You have 1 year of OPT right? Good luck in your hunt....