The creation and promulgation of the SEO tools here has led to many people noting that the results returned by the tools are often different from the results they see. This problem can be pinpointed to the datacenter at Google that is being used to get the results.
It turns out that people all over the world and those just a computer away receive different results from Google for the same search all the time. This is primarily due to datacenter fluctuations and which center your computer is connecting to.
A WebMasterWorld thread entitled Different serps from 2 PCs on same network goes into detail about how this phenomenon occurs. Our development team, meanwhile is currently searching for a solution that will help make results more homogenous for our users.