I can't ever remember making a blocking bet, but it's 2007 so maybe it's time for a change.

Opp is unknown but hasn't done anything retarded over the last few dozen hands.

Party Poker
No Limit Holdem Ring game
Blinds: $0.50/$1
6 players


Stack sizes:
UTG: $110.65
UTG+1: $229.49
CO: $100.00
Button: $15.22
Hero: $90.20
BB: $123.70

Pre-flop: (6 players) Hero is SB with
UTG folds, UTG+1 calls, CO calls, Button folds, Hero raises to $6, BB calls, 2 folds.

Flop: ($14, 2 players)
Hero bets $12, BB calls.

Turn: ($38, 2 players)
Hero checks, BB checks.

River: ($38, 2 players)
Hero bets $15?

I normally check/call there because even Stevie Wonder can see what you have when you play it the way you did. If you check the river, you might get a bet out of him sometimes.