How To Fill Text With an Image in Photoshop without Rendering the Text

There are many ways to fill text with an image or texture in Photoshop, but most of them require that you render the text layer. This technique allows your text to remain editable. These instructions should work in all versions of Photoshop from 5 forward and possibly earlier.
Difficulty: Easy
Time Required: 2 minutes


Here's How:

1. Select the Type Tool and enter some text. The text will appear on its own layer.
2. Open the image you want to use as a fill.
3. Select the Move tool.
4. Drag and Drop the image onto the document containing your text. The image will appear on a new layer.
5. Go to the Layer menu and choose Group with Previous.
6. Use the Move tool to adjust the position of the top layer.

Tips:

1. At any time you can double click the text layer in the layers palette to edit the text.
2. Instead of using an image for the fill, try a gradient, use a pattern fill, or paint on the layer with any of the painting tools.
3. By painting on the grouped layer you can change the color of individual letters or words in the text block without creating separate text layers.
4. Experiment with different blend modes on the grouped layer for interesting effects.

Source : http://graphicssoft.about.com