Android Stores

[MrTAToad]

These are some of the different Android Stores that I use :

Android Play (was Google's Android Marketplace) (https://play.google.com/store)
Once you have paid for life membership, it is pretty easy to use and your APK file appears in the store almost straight away.  It is the default store for Android users and you may have trouble getting results (AtomZ hasn't had a single download yet )
You will require graphics at 512x512, several at least 320 x 480 and optionally ones at 180x120 and 1024x500

Uploading a new (or updated program) is a bit slow - I presume it makes sure the APK file is valid first...

Amazon AppStore (https://developer.amazon.com/home.html)
This is free for the first year and around $99 after that.  Like most other Android marketplaces, your application is reviewed.  As I only joined a few days ago, I dont know how efficient Amazon are at this yet.
Filling in the form is a bit more complicated than Google Play, but nothing too taxing - it just takes time.
You will require graphics at 114x114 and 512x512, plus the usual screenshot sizes.

Soc.io (http://mall.soc.io/apps)
Again, this reviews APK files, but unlike Amazon is totally free.  It's not terribly well known but is being used.
You will require 72x72 graphics as well as either 480x800 or 800x480 screenshots.

Samsung Apps (http://seller.samsungapps.com/login/signIn.as?returnURL=/main/sellerMain.as&ssoCheck=fail)
This is only for users of Samsung Android phones.  It is free to sell free applications, but requires a long and tedious bit of forum filling to be able to sell stuff - I presume they only really want commerical companies to sell applications.
Again, software is reviewed, but unlike the other stores which also review applications, Samsung do show which stage the application is currently at. 
Also uniquely, you need to select which devices your application will run on...
They also support Windows Mobile too...

[tatakamucher]

thanks 

[MrTAToad]

Windows

AllMyApps
Just submitted AtomZ (Demo) to these people, so we'll see how it goes...

[mentalthink]

Thanks MrTatoad...

[Wampus]

A couple more:-

SlideME (http://slideme.org/)

Barnes and Noble (https://nookdeveloper.barnesandnoble.com/)

[MrTAToad]

Great!