Thanks for posting. Sorry to hear of your GMAT frustrations, though at least you had a large improvement with your 2nd exam. In terms of your profile, yes there is the starting point of IT male (not sure of your nationality?) which is common/over-represented.... so that just means you need to focus on what differentiates you from that group. It's always good to focus on people skills and people management, communication skills, teamwork.... more of the softer skills and less of the technical skills (since those are already apparent and expected from you).
You do have a lot of interesting experiences you can draw from to help you showcase other sides to you, and what you can bring to the programs. The 640 is still a challenge for top 20 schools. Certainly applicants with 640 scores are admitted every year, but it will be that much more competitive for those spots, vs 680+ spots, if that makes sense. So I certainly support an applicant applying to 1-2 'dream' schools if they have their heart set on it, and encourage them to get help with their applications if possible (either an MBA admissions consultant or at the very least, feedback from colleagues especially any who know b-schools well). But you may want to also focus on 1-3 or so schools outside the top 20 as well for better chances, OR re-think taking the exam again, especially if you scored much higher on recent practice tests (sometimes in that case your best bet is to re-take sooner rather than later).
Good luck making all of these decisions!
mbaMission Insiders Guides: http://www.mbamission.com/guides.php?category=insiders
Free Consultation: http://www.mbamission.com/consult.php