I've just finished building my new iPhone and iPod Touch apps chart site at thumblounge.com/topapps/
I couldn't find a site that let me view the top selling paid apps and most downloaded free apps for EACH of the app categories. So I've taken a feed from the iTunes App Store and output for all to see.
The really great thing is that the charts are automatically updated by Apple, so it's ALWAYS showing the the most current chart data.
The only bummer is that Apple don't provide specific data for iPod Touch Apps that would have enabled me to create a separate version for iPod Touch users.
I feature the Top 25 from each of the paid and free App Store categories. Here's a few direct links to some popular categories to get you going: