(Social)Scope Beta
Kindle
Pandora
Grooveshark
Google Voice
Flipboard
500px
Ancestry
Of my 151 total apps, those are the only Android apps I use the rest are native PlayBook.
The sideloaded android apps that I use the most are
Whatsapp
google maps/latitude
Rhapsody
Imdb
ebay
American Express
Dictionary.com
Words with Friends
NYTimes
engadget
Huffington Post
Bloomberg
I have some others, but I might as well delete them. Picked these all up from goodereader.com/apps