My sister is pregnant right now, and I had the chance to be at her ultrasound a couple weeks ago (I think it was at 20 weeks) and it was awesome. We saw the baby moving her arms, and we saw her open her mouth (the lady doing the ultrasound said she was yawning!) It was very cool... I'll be an aunt in November!
Awesome! Congratulations to your sister and whole family.
However, YOU ALREADY ARE AN AUNT.