| Repped! That is almost exactly the way I do it as well. Another way to remove the black bg is, in the original lightning document. Click, Select, Select Color Range, click on your black foreground color in the tool bar and set the fuzziness to somewhere between 100 and 200 (PS7) you may have to try a couple of different times. Click Ok and hit backspace (delete) and your bolt is now against a transparent background.
To take it farther, you can make several different lightning bolts in your same lightning document on new layers with the gradients going at other angles. By selecting the different layers and moving them into the final picture you can give the effect of the bolt splitting off of itself. This will work with both the above tut (which I liked very much) as well as my variation. | 
Crazy Closet
Parachute Panic
Linear Mode
