As a dom, it really depends on the interaction with my partner.  Especially if we have great chemistry.  One of my favorites are what gets her to love submitting.  Knowing she's going to love every second and doesn't need to think about it.  Just follow orders.

One gal I see uses a vibrator on herself while we are doing reverse cowgirl greek.

 
Indescribably incredible.

Adult Toy

A big strapon  to be used on me by by Mistress or partner

elastrator.  I love having my nuts banded in submission.  Love to worship and be humiliated as my nuts turn purple.  The pain is like nothing else.

What's yours Queen Bia