The opportunity doesn't arise that often, but I have used it to my advantage in the past.
en passant

rodders wrote:
Never really understood the move, any help ?
Well have you read the expanation of the rule from the chess rules and basics of that site? But i agree, it is slightly hard to get straight away..
Its like that: for instance say youre playing whites and youre pawn say g2has managed to cross up to square g5, then for the opponent pawn of neighbouring line h7 theres no difference it makes a move to h6 or long opening to h5 you can still beat it out of the table..i think the usefulness of that rule is providing a stronger position for your pawns then youre already developed to 5th square..

En passant can prevent an opponent from closing lines when you're on an attack.
It (yes, the en passant rule) also can be used to create a pawn weakness i.e. imagine black pawns on g7 and f6, while a white pawn is on h5; because of the en passant rule, black cannot free himself via g7-g5 as he would just lose a pawn, thus white is allowed to advantage of the weak g7 pawn by piling rooks against it leisurely.
I just made my first en passant move today and wanted ask from the players if they use it a lot? Do you think its helpful for your game or not?