A: Cards (Actions) that end your turn immediately if you play them:
Brain Transference: Star Fluxx
Clean Cup!: Wonderland Fluxx
Time Portal: Star Fluxx, Doctor Who Fluxx, TNG Fluxx, Voyager Fluxx,
What Do You Want?: Star Fluxx, Oz Fluxx, Doctor Who Fluxx
I’ll Be In My Bunk: Firefly Fluxx
I’ll Be Right Back: Fluxx Remixx
(These last two cards don’t specifically say that your turn ends immediately, but you certainly can’t continue your turn if you “Excuse yourself from the game and leave the room for a few minutes.”)
Cards (Rules) that end your turn immediately if/when you execute them, but not when you play them:
Swap Plays for Draws
Get On With it
Play All +1 (not optional, but see below)
Free Action Rules are optional, so you could choose not to use one that will end your turn immediately. While Play All +1 is not optional, you have some options about when you choose to take that final +1.
Other questions pertaining to cards which cause your turn to end immediately:
Interaction with Play All
Interaction with Hand Limits
Using immediate turn-end Actions with compound Actions like Draw 3 Play 2, etc
Using immediate turn-end New Rules with compound Actions like Draw 3 Play 2, etc
Interaction with Play All +1
Also see: