WizMouse is a free and lightweight Windows application that enables a simple but effective trick: the ability to scroll the contents of a window that is under your mouse cursor without shifting the focus to that window.
A. M. Lauer, S. J. Slee, and B. J. May. J. Assoc. Res. Otolaryngol.12(5):633--645 (October 2011)PubMed Central:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3173556PMC3173556 DOI:http://dx.doi.org/10.1007/s10162-011-0279-y10.1007/s10162-011-0279-y PubMed:http://www.ncbi.nlm.nih.gov/pubmed/2171729021717290.