A less common, but effective, overbet is when the river ensures the pot is [almost certainly] split but you represent a stronger hand.
Here is an example from this afternoon where the [tightish] villain almost certainly has an Ace but the probability of him having a 7 kicker is very slim- making the overbet a +EV move.
Full Tilt Poker, $1/$2 NL Hold'em Cash Game, 6 Players
LeggoPoker.com -
Hand History Converter
BTN: $204.35
SB: $196
Hero (BB): $188
UTG: $203.85
MP: $291.70
CO: $405.45
Pre-Flop: Q[img]/images/graemlins/club.gif[/img] 3[img]/images/graemlins/club.gif[/img] dealt to Hero (BB)
UTG calls $2, 4 folds, Hero checks
Flop: ($5) 3[img]/images/graemlins/diamond.gif[/img] 5[img]/images/graemlins/club.gif[/img] 2[img]/images/graemlins/club.gif[/img] (2 Players)
<font color="red">Hero bets $4</font>, UTG calls $4
Turn: ($13) 4[img]/images/graemlins/spade.gif[/img] (2 Players)
<font color="red">Hero bets $10</font>, <font color="red">UTG raises to $20</font>, Hero calls $10
River: ($53) 6[img]/images/graemlins/heart.gif[/img] (2 Players)
<font color="red">Hero bets $162 and is All-In</font>, UTG folds
Results: $53 Pot ($2.65 Rake)
Hero mucked Q[img]/images/graemlins/club.gif[/img] 3[img]/images/graemlins/club.gif[/img] and WON $50.35 (+$24.35 NET)