According to MacStories, the iPad's App Store app just gained a very useful new feature: search filters. There are now five different filters you can assign to app searches: Category, Release Date, Customer Rating, Price and Device. Popovers allow users to adjust or clear filters.
This added search functionality hasn't made it to the iPhone/iPod touch App Store apps yet, but considering how cramped the screens are on those devices, it might never show up. Notably, these filters also aren't yet available on the desktop version of the App Store, so right now the iPad seems like the best way to search for apps.
No update is required on your end; this is a backend change to the App Store itself, so if you're using an iPad, you should already be seeing this updated feature. Search away!