There might be many instances when you liked a font in an image and was not able to find out the font used. WhatFontis is made specifically for this purpose, it is a free online service which can find fonts from any image provided. You can submit an image with the font you are looking for and it scans and displays the font. Please note the text must be written in one line and saved in jpeg, gif or png format.
You can either upload the image from your PC or specify any image uploaded online.
You can specify to display or free fonts or all commercial fonts as well. There is an example page which shows how the fonts need to be to identify it. You also need to ensure that you qualify the tips mentioned here for the font to be identified correctly.
Note: We tried this service and was able to get fairly good results, although in some cases the service was not able to identify the correct font.