CamFind - CamFind is the very first mobile application that can photograph, identify, and provide information...
QuickMark - QuickMark makes everything possible.
IQDB - Multi-service image search
ZXing - Barcode Scanner for Android
TinEye - Reverse Image Search to help find an image's source, duplicates or altered versions.
Barcode & QR Code Scanner - A free app which allow to read and generate barcodes for Android.