Appy Days is a great way to find deals on Applications. It is a free utility that lists all the newly discounted applications for Mac and iOS. The first time that you run Appy Days, you will see a list of applications. These will show the application icon, the app category and its Mac App Store or iOS App Store rating, along with the previous price, current price and discount percentage. There are links that will take you to the Mac App Store to buy that app. One very nice thing about Appy Days is that the developers managed to add a variety of filters that make searching for apps and grouping those that you like an easy task. For example, on the left pane, you can select whether you want to see Mac, iPhone or iPad apps, whether you want free or paid apps, and you can even select the minimum star rating. From a drop-down menu, you can select the app category to narrow down the results even more. If you check the "Show popular apps only" button, only those applications that have been recently popular on the App Stores will be displayed, but you get a warning saying that you can probably miss on other great apps if you check this button. Once you have narrowed down your list of results enough, and you are not sure if you want to buy an application, you can add it to a favorites list or even mark it to buy it later.
In short, Appy Days is a great way to discover new apps on the App Stores. It has a great design and great filtering capabilities.