The Lightning Conductor Web Part allows you to aggregate data from Lists and Libraries throughout the current Site Collection, and across Multiple Site Collections.  If you want to see all of your Tasks in one Web Part, instead of navigating to lots of different sites to view your Tasks list, the Lightning Conductor Web Part can perform that for you.

You can base the Lightning Conductor Web Part on List Types, or Content Types, Filter the data based on any column in the List or Library, and apply styles to the Web Part, or create your own styles.