I'm still investigatng wich on camera lightning i should use for shoting weddings. I like my Canon XL2 but know also that i should use some extra light.

I suppose that there are enough of you out there that has the knowledge wich lightning i should use on my XL2 without disturbing to much the ceremony of the wedding.

I would apreciate if someone can suggest me a good on camera lightning.

You might want to try the board labeled Photon Mangement. It is the board dealing with lightning.