Together with the Christmas specials, it's become a tradition for Doctor Who to deliver a mini-episode during the BBC's three major telethons (Comic Relief, Sport Relief and Children In Need.) Keeping that custom alive, the excellent Steven Moffat-penned charity special "Space & Time" just aired on Red Nose Day, showing us what would happen if the TARDIS accidentally materialized within itself.
I like how Moffat uses these specials to tackle ideas that perhaps wouldn't fuel a normal-length episode, but instead scratch geeky itches. Oh, and who doesn't want to see two Amy Ponds flirting with each other? You can watch the very "timey-wimey" seven-minute video above and below.