ZXing - Barcode Scanner for Android
Yandex.Images - search for images on the internet, search by image
Barcode to PC: Wi-Fi scanner - Turn your smartphone into a real barcode scanner
TinEye - Reverse Image Search to help find an image's source, duplicates or altered versions.
bcWebCam - Scan barcodes and QR Codes with your computer web cam
SauceNAO - SauceNAO is a reverse image search engine.