Dialog modality curtains should fade in and out.
Dialogs should slide down and slide back up when done.
(Such as editing a user in security app)

Confirmations should fade in with a slight zoom and fade out with a slight zoom out.
(Such as delete confirmations)

Notifications should slide down from the top - and fade out when done.

Transitions can be implemented with css3 animations.

These transitions are very simple and can be implemented simply by applying css styles.