A Stimulator????

A guy at our weekly fly tying class gave me a Stimulator pattern and a little nymph to use as a dropper off the back (attached via a piece of tippet tied to the bend of the hook of the Stimulator). The nymph is about a size 16, little black glass bead and dubbed body, really tied nicely. What other little nymphs do you put on the dropper that are effective? What is the best way to tie on the dropper? Is there a special knot for this to keep it from slipping?

I have never used this type of setup before but apparently it is highly effective on brookies.

Thanks,

Dwight