Power Control Plus widget ($1.99 I think) has more and customizable widgets than the basic one included with the phone, and one of them is Flashlite. I had Tiny FL, but just use this since I use the other buttons on it.
I used to use Tesla, had issues with the light going off when the screen locked. I think the one I have now is just called Flashlight. All I did was go to the app market and downloaded the highest free one.