Wordpress - Front-End Post Submission

<?php $postTitle = $_POST['post_title'];
$post = $_POST['post'];
$submit = $_POST['submit'];

if(isset($submit)){

    global $user_ID;

    $new_post = array(
        'post_title' => $postTitle,
        'post_content' => $post,
        'post_status' => 'publish',
        'post_date' => date('Y-m-d H:i:s'),
        'post_author' => $user_ID,
        'post_type' => 'post',
        'post_category' => array(0)
    );

    wp_insert_post($new_post);

}

?>
<!DOCTYPE HTML SYSTEM>
<html>
<head>
<meta content="text/html; charset=utf-8" http-equiv="Content-Type" />
<title>Untitled Document</title>
</head>

<body>
<div id="wrap">
<form action="" method="post">
<table border="1" width="200">
  <tr>
    <td><label for="post_title">Post Title</label></td>
    <td><input name="post_title" type="text" /></td>
  </tr>
  <tr>
    <td><label for="post">Post</label></td>
    <td><input name="post" type="text" /></td>
  </tr>
</table>

<input name="submit" type="submit" value="submit" />
</form>
</div>

</body>
</html>

I found this at Themeforest it's working fine,
you can do a lot of things with this, you have to add some extra code to check if a user is logged in or whatever you want to do,

In the other hand you have to search in the WordPress plugins repo to find out some great plugins,
Search for "frontend"

hope it helps