I wish I had some good Sins stories to tell, but I haven't played much lately.  Sadly, it's getting harder and harder to find 4v4 and 5v5 games, so they'll be fewer and fewer stories, and I haven't seen any replays posted lately.  If you read through older threads in the Multiplayer forums you're liable to find a couple stories, especially if you find the replays thread.  However, those replays from earlier versions of the game won't work in the current versions of the game.  If you learn to play it in online multiplayer, you might be able to tell some of your own stories one day.  You might one day be able to tell tales about:

• How an underdog team beat a group of vets, causing some of them to pull out their ethernet cables.
  
• How a single large battle at a choke point determined the outcome of a game.
• How a team's best player was knocked out early-on by a double-team Skinatra rush.
• How a player who started in the "suicide spot", wedged between four opponents, held out and essentially won the game for his team.
• How an exploding TEC starbase turned a game around.
• How a dual Marza missile barrage won the game.
  
• How a player who started in a suicide spot managed to migrate to another star, become strong, and return to help his team to victory.
• How a game was locked up until a Vasari player was able to attain Returning Armada, powering his team to victory (Sins games before v1.1).
• How a player built 10 Kosturas and used them to demolish enemy fleets.

...and those are just a sampling of some of the stories I have experienced.