What we do is: My wife will put on this toy like a thong panty. I lay back against the pillows on my bed with my legs spread and head just high enough to watch the action. She gets between my legs on her elbow's and knees and starts sucking me. She keeps one hand around my cock, and she has the other on the controller of the toy. This toy takes 3 AA batteries, so trust me it has plenty of power. She then rocks back and forth and sucks my cock while this thing is buzzing her clit. I am fairly large, and she cannot usually take me all the way down. But when she starts to orgasm she is ramming my cock down her throat, which of course sends me over the edge. For me the site of her sucking my cock, and getting off at the same time is amazing, add to that her "bliss enhanced deep throat ability" and the fact that I almost always cum at the exact same time as her doing this..... this rules.
For her, she really likes how this toy fits against her pussy, and how when she rocks forward and backwards to suck my cock it causes the toy to tighten and slightly loosen against her clit. So her pace usually starts off really slow with the toy on low, and by time she is cumming she is rocking 100 miles per hour! She also says it's an awsome feeling having my cock in her mouth while she cums!
The below toy is called the Mini Hummer. It is for sale on the internet for about $30 (I do not have any vested interest, It is just one of those things I want to share with other couples!)
This is a thong designed strap on clit buzzer. We have found that the thong design stays in place snug against her clit much better than the kind that use the straps that go around her thighs (venus butterfly's). Also, this is kind of a ridged design, that kind of spreads her open.
If you try this, please share your experience here!