http://www.excelcampus.com/tools/sumifs-countifs-averageifs-filter-analyzer-add-in

Free Excel add-in that quickly filters the source data for any SUMIFS, COUNTIFS, or AVERAGEIFS formula, and lists the fields and criteria for easy analysis and troubleshooting. This will save you lots of time when working with these long IFs formulas that can be difficult to read.

To learn more on how to use the IFs functions, checkout some of the great videos my Mike Girvin at ExcelIsFun. http://www.youtube.com/user/ExcelIsFun/search?query=sumifs