[Mean]

pawn Код:

new 
    oldmoney[ MAX_PLAYERS ]
    ,newmoney[ MAX_PLAYERS ]
;

public OnPlayerUpdate( playerid ) {
    newmoney[ playerid ] = GetPlayerMoney( playerid );
    if( oldmoney[ playerid ] != newmoney[ playerid ] ) {
        new 
            difference = newmoney[ playerid ] - oldmoney[ playerid ]
            ,pName[ 24 ]
        ; 
        GetPlayerName( playerid, pName, 24 );
        printf( "Player %s has just earned/lost $%d.", pName, difference );
    }
    oldmoney[ playerid ] = GetPlayerMoney( playerid );
    return 1;
}

Untested, this should detect when a player gets/looses some money.