AppShopper - Mac Apps, Mac App Store, iPad, iPhone and iPod touch app store listings, news, and price drops
Just Install - just-install - The stupid package installer for Windows.
Apple Sliced - Apple Sliced searches the Web for the lowest prices and uses only Authorized Apple Resellers, so...
Scoop - A command-line installer for Windows
Knicket App Search - The future Wikipedia for Apps
Windows Remix - Web-based batch software installer with zero dependencies. Recommended first visit after reinstalling Windows or buying a new laptop.