splitfeed

This plugin requires a Gmail account connected to a phone from which you can get your 
<a href="http://code.google.com/p/android-market-api-php/wiki/HowToGetDeviceID#market_checkin" rel="nofollow ugc">market_checkin value</a>. As far as I know this can only be done (reasonably) easy on rooted devices
Adds a shortcode to display a generated image containing information from the Android Market. The shortcode format is [app]<app pname>[/app] 
to output a badge of the selected application. 
There is also a simple support for QR-codes built in that can be used by [qr]<app pname>[/qr].
<h3>Examples</h3>
[app]org.wordpress.android[/app]
[qr]org.wordpress.android][/qr]
[qr size=10]org.wordpress.android][/qr]
<ul>
<li><a href="http://www.splitfeed.net/market-badges/" rel="nofollow ugc">Plugin web page</a></li>
</ul>

Android Market Badges

Adds a BBcode to display a generated image containing information from the Android Market.

dcoupe

With appwidget you can easily share your Android app on your blog posts.
For example if you need to promote the Appchina app ( Market link for Appchina ) which has com.yingyonghui.market as package name, you only need to insert com.google.android.youtube in your editor and it will generate: * icon * name * developer * rating of the app.
Website: http://i.appchina.com/wp-plugin/

appwidget

This plugin lets you easy access to information on any Android application the appchina.com market.

Android Market Badges vs appwidget