If you want to secretly take pictures with your Android phone, download 'Spy Camera'. It has no preview and no shutter sound. You only see a black screen with a status and free space indicator, or you can even completely turn off the screen!
It comes with many features:
It shows as 'Sca' on your phone, not 'Spy Camera', so no one will know what it is.
It's not listed in the recent apps list.
You can prevent the pictures from showing in the 'Pictures' or 'Gallery' app. You'd have to connect your phone to the computer to see the pictures.
It can take pictures continuously, and you can specify a delay in between each picture.
You can also lock the app so it ignores all input and looks like the phone is simply in sleep mode.
You can find 'Spy Camera' in the Market at
or scan the barcode below with your phone to view it in the Market.