i have recently found out about the Aviary Photo Editing SDK for Android.
Check it out at http://developers.aviary.com/.
I have quickly put together a nice little app which makes use of this SDK.
The Aviary SDK supports things like adding stickers, text, various photo effects, cropping, rotating, drawing, etc...
You can select your local photos or choose to browse your Facebook photos and those of your Facebook friends.
It also easily integrates with all your existing photo apps: simply use the share/send function of those apps and choose Easy Photo Editor to handle it
Check it out at https://market.android.com/details?id=de.goddchen.android.easyphotoeditor or use the qr code
Looking forward to your feedback! Feature requests, bugs, etc...