Mobile application recommendation websites and services have sprung out of a growing need to filter, rank and recommend the best apps from the hundreds of thousands now available for download onto mobile phones. These sites operate outside of the official app marketplaces like the iTunes App Store and the Android Market, for example.

With iTunes now carrying 225,000 apps in its "curated" collection and Android up to 100,000, it's no wonder users have turned to other resources beyond the search box and category listings found in the official vendor-specific app stores. For the end users, recommendation sites like these prove useful, even necessary at times.

But are these sites helping developers? And if so, how much?

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To determine the usefulness of these sites, we spoke to the execs behind several of the leading recommendation services. Each site offers its own feature set and ranking algorithm. Some, for example, not only take into account an app's popularity, but also its media coverage when ranking the apps. Others use a combination of signals including apps you own and members' reviews in their algorithms.

Here are our findings, broken down by site or service.

AppStore HQ

AppStoreHQ is a site featuring apps for Android, iPhone, iPad and even Web-based HTML apps. Here, you can find what apps are hottest on the Web (mentioned by press or blogs), what are hottest on Twitter and it offers app reviews. AppStoreHQ currently gets 836,000 visits per month.

Chris DeVore, the site's CEO and co-founder, pulled some data for us about the app downloads. According to the data, the apps in the sponsored results (basically, ads for apps), receive more than 28 times the downloads of the average app. That means that buying a sponsored result on their site is as effective as being in the site's "Top 100 Hottest" list when it comes to driving views and downloads.

Some other stats they rounded up:

In indexed terms, where 100 is the baseline:

  • Average number of views/week for apps that get any views: 100
  • Average number of views/week for apps in the top 100 hottest list: 579
  • Average number of views/week for apps listed as sponsored results: 631
  • Average number of downloads/week for apps that get any downloads: 100
  • Average number of downloads/week for apps in top 100 hottest: 250
  • Average number of downloads/week for apps with sponsored result: 2,867

Appolicious

Yahoo partner Appolicious ranks and recommends iPhone, iPad, Android and Yahoo applications using a number of mechanisms, including reviews, likes (its own, not Facebook's) and friend recommendations. Users can follow their friends on the site and train the recommendation engine by sharing what apps they already have installed. Then, when signed in, the site can recommend new apps to try based on your preferences, what apps you own and other signals.

CEO Alan Warms says that on any given day, 10% of the users who visit the site end up downloading an app. The apps reviewed in Appolicious' editorial section see the best numbers. The editorial section doesn't sell its reviews - it showcases apps based on what the writers find appealing. Apps in this section and others that are well-known, like an Angry Birds type app, see five times the number of downloads as others on the site. Meanwhile, apps that are new to the audience see an increase of 10 to 15 times the downloads when they arrive to the site.

Chomp

Chomp (disclosure: Chomp is a RWW sponsor) is an app discovery engine that combines app search with personalized recommendations. An accompanying iPhone application was released in January 2010. Developers can use Chomp to automatically prompt app users to review the app after a set number of launches.

Each app featured on the site has its own page with screenshots, a description and its iTunes reviews. These reviews are then rated, in aggregate, by Chomp, displaying either a red heart (for positive reviews) or a broken heart (for negative reviews) to reach a combined score. It then can recommend an app as being overall more positive than negative.

Chomp and Appolicious (above) were also recently featured in the The Wall Street Journal. Unfortunately, Chomp was unwilling to share any of its data with us.

AppsFire

AppsFire isn't quite like the others. It's not just a website, but also an iPhone application that allows users to discover and share the best apps. According to co-founder Ouriel Ohayon, the site sees 1.5 million clicks (they call that download intentions) per month to the app developers page. "This is the only metric with downloads that matters," says Ohayon.

He also notes that the service has reached a point where it's able to boost the position of an app in the iTunes App Store top rankings in just a few hours. One example was when "Say it & Mail it Recorder" partnered with AppsFire to boost downloads by dropping its price to zero for a short time. In another example, a partnership with "Beautiful Panoramas" made it to the top 50 lists and number two in the Photography list in iTunes in less than three hours. AppsFire's advertising service also does well.

Smokin Apps

Smokin Apps features the top mobile apps for iPhone, Android, Blackberry, Nokia, Palm and Windows Mobile. Smokin Apps just sold to new owners, so it's in a transition period right now. However, even without a brand-name affiliation like Appolicious has with Yahoo, for instance, the site has been driving large numbers of downloads to the apps it showcases.

The site's recommendation engine matches you with apps you would like based on apps similar to those you own. It then combines that information with other members' recommendations using an algorithm that tracks every way users rate apps on the site. The end result is personalized recommendations of new apps to try. According to Smokin Apps' Ash Conway, the top 10 apps by page views over the past year included the following (see below). Next to each apps is the number of downloads the app saw and whether it was free or paid:

  • Words with Friends: PV30,620/DL252/Paid
  • Chase Mobile: PV16,578/DL3061/Free
  • Police Scanner": PV15,351/DL499/Paid
  • Scrabble: PV13,023/DL1776/Paid
  • Talking Carl: PV12,712/DL456/Paid
  • Hipstamatic: PV10,550/DL209/Paid
  • Red Laser PV5,553/DL176/Paid
  • Live Poker by Zynga: PV3,485/DL476/Paid
  • Ootunes: PV3,430/DL59/Paid
  • Text Plus: PV3,200/DL741/Free

Although this is just a sample of the app recommendation sites out there, you can see that getting an app on these sites can often help you achieve more downloads than just submitting to a mobile app store alone. When even sites as small as Smokin Apps can deliver thousands of pageviews, then it follows that larger app sites can do even better.

More importantly, apps that feature true "recommendation engine" components (i.e. algorithms) prove even more useful for matching end users with app they like. Do you have a favorite app recommendation site or service? If so, let us know which one and why.