<input type="checkbox" name="days[]" class="other" value="Monday" /> 
   <label class="left">Monday</label> <br /> 
   <input type="checkbox" name="days[]" class="other" value="Tuesday" /> 
   <label class="left">Tuesday</label> <br /> 
   <input type="checkbox" name="days[]" class="other" value="Wednesday" /> 
   <label class="left">Wednesday</label> <br /> 
   <input type="checkbox" name="days[]" class="other" value="Thursday" /> 
   <label class="left">Thursday</label> <br /> 
   <input type="checkbox" name="days[]" class="other" value="Friday" /> 
   <label class="left">Friday</label> <br /> 
   <input type="checkbox" name="days[]" class="other" value="Saturday" /> 
   <label class="left">Saturday</label> <br /> 
   <input type="checkbox" name="days[]" class="other" value="Sunday" /> 
   <label class="left">Sunday</label> <br /> 

$days = implode(",",$_POST['days']); 
.
.
mysql_query("INSERT INTO users (..., days, ...) VALUES (.., '$days', ..)") or die("something went wrong during the registration. MySQL said: ".mysql_error()); 

$result =  mysql_query("SELECT * FROM users where verified = 0");
while($info = mysql_fetch_array($result, MYSQL_ASSOC)) {
.
.
.
	$days = explode(",", $info['days']);
	foreach ($days as $value){
		echo $value;
		echo "<br/>";
	}
.
.
.
}

$a=0;
foreach ($days as $value){
$a=$a+1;
}
for($i=0;$i<$a;$i++) 
{
echo $days[$a];
echo "<br/>";
}

$days_array = array("");
foreach ($_POST['days'] as $val2){
	$days_array[] = $val2; 
}
$days = implode(",",$days_array);