All following data was collected by myself from open sources including NRMP reports and available Match 2012 results.
What is IMG-Friendly?
Term IMG-friendly is used to describe medical specialties with highest chances for IMG to get into. Highest percent of IMGs means that medical field is more friendly for foreign applicants.
In following table you can see medical specialties with the highest percentage of IMGs among all matched applicants and their average USMLE Step 1 scores.
Match 2012 Statistics shows that there is really strong relationship between USMLE Step 1 score of an applicant and his Match success. But this relationship should not be overestimated, because residency program directors consider other qualifications of applicants and high USMLE Step 1 score is no more a mandatory for successful Match.
In other words, if you are an IMG - you should do your best at USMLE Step 1 exam, but even high score cannot guarantee a successful Match.