What are the alternative Android app markets?

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I use AppBrain because it provides a nice site, and it makes it really easy to install apps onto my phone. Additionally, I'm finding that many bloggers that are reviewing apps are putting links to the AppBrain page for the app in their posts. This makes it really easy to mark something for install while I'm at my computer reading the blog posts, and then install it when I get a chance.

^{Edit by Izzy:}

AppBrain offers an alternative (and much cleaner) interface to the Google Play Store, which offers several advantages:

• search results are much less limited (30 pages à 10 apps = 300 results, much more than Play offers)
• search results "gray out" possible spam, offensive, and otherwise harmful apps. You still can see them, though – but it's quite clear what to skip
• app details page gives the most important details at a glance. It's easy to see what permissions are requested. And if those form "potential dangerous combinations" (called "concerns" at AppBrain), that's automatically pointed out by a warning sign on the permissions tab
• Their app (an alternative to the Playstore app) enables you to skip single (or all) updates on a per-app-base, which keeps your list of "pending updates" quite clean.

For installation, you will be redirected to Google Play. In the past, AppBrain had a separate app for this called the "Fast Web Installer", but unfortunately this app was banned by Google. So even for batch updates, the Playstore app will now be opened for each app separately (not AppBrains fault).

^{AppBrain App Market (source: AppBrain; click images for larger variants)}

Still, I count their Website as a much better alternative to the Google Play website – and the same is to be said for their app, though for installations it has to redirect you as described above.