Pardon the self-promotion, but I can't help but point to the latest episode of Virtual Play.  I use the Spirit of the Century adventure "Rex Rich and the Warlord of Mars" that my brother, Bill White, ran at Dreamation to highlight two scenes involving gamemaster force and player choice.  In the first scene, Bill prevents a player from depicting his character's action through simple GM fiat or, what could charitably be called aggressive scene framing.  The second scene involves similar GM influence over a player character's action, but this time the influence is based on the use of a Compel and the rewarding of a Fate Point.  I think the two examples provide a nice contrast that demonstrate how useful Compels can be in shaping the plot.  And between those two examples are a bunch of other cool moments of play!  And all of this is meant to demonstrate how much fun SOTC is to play!  But I don't need to tell you that. 
Mel