I am not sure when I started using this pattern but it works well to get some one to fold on the river.
(I often use it when on a draw and I miss.)

Preflop - Medium Bet (2xBB or 3xBB)
Flop - Medium Bet (2xBB or 3xBB)
Turn - Check
River - Bet Half Pot if everyone else has Checked the Turn

It seems like people fold over 80% of the time when I follow this pattern. I feel that people think I was trying to set a trap on the turn and now am betting to get some money for my hand.
(Also, I find if I make too big of a bet, people think I am bluffing or trying to steal the pot and call my bet.)

Has anyone else used this pattern? Thoughts?