"Timescape" is one of my favorite TNG episodes. After attending a conference away from the "Enterprise," Troi, Picard, Data and LaForge find that time is standing still for them aboard their shuttle. They discover the same thing has happened aboard the "Enterprise" as they assist a Romulan Warbird. One of the best parts of the episodes is watching the ship explode and then get put back again as time moves backward.
I also liked the scene where Picard feels the effect of the 'temporal narcosis' and draws the happy face on the plasma cloud. Just a fun, exciting episode to watch.