Vidic - vs Liverpool, 2008/09, allowing the ball to bounce, getting murked by Torres, losing the ball as the last man. Torres goes on to score, we lose a huge match in the title run-in 4-1, at home.
Ferdinand - vs City, 2009/10, tries to scoop the ball over Bellamy's head in the last minute of a Manchester Derby. Bellamy takes the ball, speeds past Rio, and equalizes. Luckily we scored in the 7th minute of injury time.
Stam - vs Arsenal, 1999/2000, robbed by Ljungberg at OT against Arsenal, when he was the last man. Ljungberg went through and scored.
I am not trying to be a wise arse, but these are examples that are literally right off the top of my head!