Just to help out, Miscojobs.com is a great site for petroleum engineers. Pay the fee they ask, it'll be worth it....
I got one of those ... where did you go? Network with other people and start a company. Learn from people that have already done it. Not that you really need an MBA to do that, but not all of us are the next Bill Gates.
FYI This was asked in the past with a bajillion responses. Check it out : http://bbs.clutchfans.net/showthread.php?t=157857
I have a BSEE and am getting an MBA. If you're seriously going to take a paycut by switching over to marketing/finance - you should stay at your job. That being said, i don't know ANY engineer outside of an engineering manager (where an MBA would still be useful), that makes as much as a post-MBA finance/marketing guy.