1. Start with an existing image or just create a new image. I used 400 x 125 and filled the background with black for this tutorial. And I have added my text. And used white for text.
2. Now duplicate the text layer 1 time, and rasterize the copy. Make sure you place the original text on the top like so.
3. On the rasterized layer go to Filter > Blur > Gaussian blur and use these settings
You should have something like this now
4. Now on the text copy go to the blending options and use these settings. I selected white for the outer glow.
And you are done. Here is my final result
Here are a few other examples just by changing the color of the outer glow in the blending options
More Tutorials: 
