To avoid using someone else's copyright protected images you aren't allowed to use for commercial or even personal use, Google Advanced Image Search has got you covered.
If you know how to sing or hum a song, but don't know the title or the artist performing it, you can use a midomi website which will help you find the the song.
Camera images usually contain additional description about camera settings and scene information of the the picture taken. By using EXIF, you can view this data online.
