try selecting an edge and hit "Edge Loop Split". this would be the most used function from MJPolyTools I guess.
another script I use constantly for modeling is SpinFaces.mel
you can find it at https://www.knower.it/ in the digital art section.
TemplateSkeletonLE.mel by Paul Thuriot is a must for rigging.
everything starts and ends in the right place at the right time.