For us Microsoft Excel power users, this seems pretty useful.

Yahoo! MapMaker for Excel is a Microsoft Excel template that enables any user of Excel to plot data on a Yahoo! map without programming. Just enter geographic data (up to 100 locations) into the spreadsheet, and after a few clicks, whammo, instant map...You can provide address/city/state, latitude/longitude pairs, or a column containing nothing but ZIP codes. Optionally you can assign titles and descriptions to each map point.