I just finished watching Day Break, which is kind of like a cross between a crime/conspiracy drama and Groundhog Day (in the science-fiction sense, not the romantic-comedy sense). The main character, Detective Brett Hopper, wakes up one morning to find he's been framed for murder, so he sets out to clear his name, uncover the truth, and protect his family (who are getting some attention because of the first two). The twist is that he keeps reliving the same day over and over again, with his memories (and injuries) intact. Changes he makes in one iteration affect the next (and can be reverted by subsequent actions).
The show was canceled after 6 episodes aired; 13 had been made and eventually came out on DVD (which I've been watching via Netflix). The final episode reaches a satisfying ending while leaving doors open; I presume it was intended to be the finale of a short season when it was made. So it fared better than many shows that get canceled early in that it tells a story rather than just the first few chapters of a story. It had potential, though, and it would have been interesting to see a second season.
The episodes that were made do not, however, provide any insight into what is causing the time loop. I wonder if we were ever going to learn about that or if it was just meant to be one of the givens of the show.