Task: Forest fire
Java: import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

public class Fire {
	private static final char BURNING = 'w'; 
	private static final char TREE = 'T';
	private static final char EMPTY = '.';
	private static final double F = 0.2;
	private static final double P = 0.4;
	private static final double TREE_PROB = 0.5;
	
	private static List<String> process(List<String> land){
		List<String> newLand = new LinkedList<String>();
		for(int i = 0; i < land.size(); i++){
			String rowAbove, thisRow = land.get(i), rowBelow;
			if(i == 0){
				rowAbove = null;
				rowBelow = land.get(i + 1);
			}else if(i == land.size() - 1){
				rowBelow = null;
				rowAbove = land.get(i - 1);
			}else{
				rowBelow = land.get(i + 1);
				rowAbove = land.get(i - 1);
			}
			newLand.add(processRows(rowAbove, thisRow, rowBelow));
		}
		return newLand;
	}

	private static String processRows(String rowAbove, String thisRow,
			String rowBelow){
		String newRow = "";
		for(int i = 0; i < thisRow.length();i++){
			switch(thisRow.charAt(i)){
			case BURNING:
				newRow+= EMPTY;
				break;
			case EMPTY:
				newRow+= Math.random() < P ? TREE : EMPTY;
				break;
			case TREE:
				String neighbors = "";
				if(i == 0){
					neighbors+= rowAbove == null ? "" : rowAbove.substring(i, i + 2);
					neighbors+= thisRow.charAt(i + 1);
					neighbors+= rowBelow == null ? "" : rowBelow.substring(i, i + 2);
					if(neighbors.contains(Character.toString(BURNING))){
						newRow+= BURNING;
						break;
					}
				}else if(i == thisRow.length() - 1){
					neighbors+= rowAbove == null ? "" : rowAbove.substring(i - 1, i + 1);
					neighbors+= thisRow.charAt(i - 1);
					neighbors+= rowBelow == null ? "" : rowBelow.substring(i - 1, i + 1);
					if(neighbors.contains(Character.toString(BURNING))){
						newRow+= BURNING;
						break;
					}
				}else{
					neighbors+= rowAbove == null ? "" : rowAbove.substring(i - 1, i + 2);
					neighbors+= thisRow.charAt(i + 1);
					neighbors+= thisRow.charAt(i - 1);
					neighbors+= rowBelow == null ? "" : rowBelow.substring(i - 1, i + 2);
					if(neighbors.contains(Character.toString(BURNING))){
						newRow+= BURNING;
						break;
					}
				}
				newRow+= Math.random() < F ? BURNING : TREE;
			}
		}
		return newRow;
	}
	
	public static List<String> populate(int width, int height){
		List<String> land = new LinkedList<String>();
		for(;height > 0; height--){
			StringBuilder line = new StringBuilder(width);
			for(int i = width; i > 0; i--){
				line.append((Math.random() < TREE_PROB) ? TREE : EMPTY);
			}
			land.add(line.toString());
		}
		return land;
	}
	
	
	public static void processN(List<String> land, int n){
		for(int i = 0;i < n; i++){
			land = process(land);
		}
	}
	
	
	public static void processNPrint(List<String> land, int n){
		for(int i = 0;i < n; i++){
			land = process(land);
			print(land);
		}
	}
	
	
	public static void print(List<String> land){
		for(String row: land){
			System.out.println(row);
		}
		System.out.println();
	}
	
	public static void main(String[] args){
		List<String> land = Arrays.asList(".TTT.T.T.TTTT.T",
				"T.T.T.TT..T.T..",
				"TT.TTTT...T.TT.",
				"TTT..TTTTT.T..T",
				".T.TTT....TT.TT",
				"...T..TTT.TT.T.",
				".TT.TT...TT..TT",
				".TT.T.T..T.T.T.",
				"..TTT.TT.T..T..",
				".T....T.....TTT",
				"T..TTT..T..T...",
				"TTT....TTTTTT.T",
				"......TwTTT...T",
				"..T....TTTTTTTT",
				".T.T.T....TT...");
		print(land);
		processNPrint(land, 10);
		
		System.out.println("Random land test:");
		
		land = populate(10, 10);
		print(land);
		processNPrint(land, 10);
	}
}

PHP: <?php

define('WIDTH',      10);
define('HEIGHT',     10);

define('GEN_CNT',    10);
define('PAUSE',  250000);

define('TREE_PROB',  50);
define('GROW_PROB',   5);
define('FIRE_PROB',   1);

define('BARE',      ' ');
define('TREE',      'A');
define('BURN',      '/');


$forest = makeNewForest();

for ($i = 0; $i < GEN_CNT; $i++) {
    displayForest($forest, $i);
    $forest = getNextForest($forest);
}

displayForest($forest, 'done');
exit;


function makeNewForest() {
    return mapForest([
        'func' => function(){
            return isProb(TREE_PROB) ? TREE : BARE;
        }
    ]);
}


function displayForest($forest, $generationNum) {
    system("clear");
    echo PHP_EOL . "Generation: $generationNum" . PHP_EOL;
    mapForest(['forest' => $forest, 'func' => function($f, $x, $y){
            echo $f[$y][$x] . ($x == WIDTH - 1 ? PHP_EOL : '');
        }
    ]);
    echo PHP_EOL;
    usleep(PAUSE);
}


function getNextForest($oldForest) {
    return mapForest(['forest' => $oldForest, 'func' => function($f, $x, $y){
            switch ($f[$y][$x]) {
                case BURN:
                    return BARE;
                case BARE:
                    return isProb(GROW_PROB) ? TREE : BARE;
                case TREE:
                    $caughtFire = isProb(FIRE_PROB);
                    $ablaze = $caughtFire ? true : getNumBurningNeighbors($f, $x, $y) > 0;
                return $ablaze ? BURN : TREE;
            }
        }
    ]);
}


function getNumBurningNeighbors($forest, $x, $y) {
    $burningNeighbors = mapForest([
        'forest' => $forest, 
        'x1' => $x - 1, 'x2' => $x + 2,
        'y1' => $y - 1, 'y2' => $y + 2,
        'default' => 0,
        'func' => function($f, $x, $y){
            return $f[$y][$x] == BURN ? 1 : 0;
        }
    ]);
    
    $numOnFire = 0;
    foreach ($burningNeighbors as $row) {
        $numOnFire += array_sum($row);
    }
    return $numOnFire;
}


function mapForest($params) {
    $p = array_merge([
        'forest' => [], 
        'func' => function(){echo "default\n";},
        'x1' => 0,
        'x2' => WIDTH,
        'y1' => 0,
        'y2' => HEIGHT,
        'default' => BARE
    ], $params);
    
    $newForest = [];
    for ($y = $p['y1']; $y < $p['y2']; $y++) {
        $newRow = [];
        for ($x = $p['x1']; $x < $p['x2']; $x++) {
            $inBounds = ($x >= 0 && $x < WIDTH && $y >= 0 && $y < HEIGHT);
            $newRow[] = ($inBounds ? $p['func']($p['forest'], $x, $y) : $p['default']);
        }
        $newForest[] = $newRow;
    }
    return $newForest;
}


function isProb($prob) {
    return rand(0, 100) < $prob;
}