To get more detailed sales figures online, one has to leave the major news outlets and go to a new upstart like VGCharts. Started last summer, VGCharts uses a proprietary system of "internal tracking, public tracking data, publisher information, analyst data, historic trend fitting and a little bit of insight and interpolation" to estimate specific monthly hardware and software unit sales "as meticulously and accurately as possible."
VGCharts represents the best good faith effort yet to publicly aggregate and organize disparate data into a searchable database of our industry's business history. Here we find all the in-depth and detailed data missing from the magazine and web site reportsmonthly unit sales for hundreds of software titles (not just the top 10); historic hardware numbers going back to 1994; even a handy graphing function that lets you compare system and game sales at similar points in their lifecycles. Yes, the site is new and has yet to build a reputation for accurate sales data, but the numbers seem to generally match with those from NPD and other sources, as far as they are comparable.