D90 with D40 as flash slave?

I have a Nikon D90 and D40, is it possible to use the D40 as a second flash like in slave mode (to just use the flash?)

Whatchutalkinaboutwillis?

I suppose you could connect a remote trigger release to the D90 and the D40 (if it will accept a wired remote), then both cameras would fire/flash at the same time.

But why?

On camera flashes are not that powerful, and you would have to put everything into manual to ensure sufficient light output, etc.

Seems you would be better off just buying a dedicated flash. You'll have $100 wrapped up into shutter triggers.

And you could buy a more powerful off-brand slave flash for under $100.