Código PHP:
Ver original<?
if(isset($_POST['Submit'])){ foreach ($_POST['seleccion'] as $id){
echo $id."<br>";
}
}
?>
<form action="" method="post">
1 <input type="checkbox" name="seleccion[]" value="1">
2 <input type="checkbox" name="seleccion[]" value="2">
3 <input type="checkbox" name="seleccion[]" value="3">
<input type="submit" name="Submit" value="Enviar">
</form>