It's not often that I find a major network primetime drama interesting (the last one was "The Black Donnellys", and it was canceled because it was so good). But I recommend that everyone watch "Life on Mars". Like 25% of all good TV shows, it's based on a previous British version. Basically, this detective is hit by a car and wakes up in 1973.  Stumbling around in a reality where 8-tracks are common and hippies openly roam the streets, where sexism and misogyny are widespread in the establishment, the twin towers still stand and puns involving the phrases "where is my CELL phone" and "you want to SELL something???" rein supreme, he wakes up in period costume, with period ID and a period car and period apartment in his name, and a job lined up in the very precinct where he worked in 2008.  

After a brief panic, he has to investigate a murderer who uses the same MO as the guy who (maybe?) killed his partner/girlfriend in 2008. It soon becomes apparent that the 2008 killer is the protege of the guy he busts in 1973. The scene where he considers killing the child version of a future murderer is super cool tense.

I can't wait until he faces the moral conundrum of having to reveal the future events of September 11, Watergate, or, God help us, the 2004 Boston Red Sox World Series win, to his mustachioed, ridiculously sexist, fourth-amendment-ignoring police officer colleagues in a world of well-maintained classic cars and thrift-store quality nehru jackets. 

In short, watch an episode or so of this show before it is canceled.