WP Collection of Code for functions.php [1]

add_custom_post_types_to_dashboard.php

<?php
// ADD CUSTOM POST TYPES TO THE 'RIGHT NOW' DASHBOARD WIDGET
function wph_right_now_content_table_end() {
 $args = array(
  'public' => true ,
  '_builtin' => false
 );
 $output = 'object';
 $operator = 'and';

 $post_types = get_post_types( $args , $output , $operator );
 foreach( $post_types as $post_type ) {
  $num_posts = wp_count_posts( $post_type->name );
  $num = number_format_i18n( $num_posts->publish );
  $text = _n( $post_type->labels->singular_name, $post_type->labels->name , intval( $num_posts->publish ) );
  if ( current_user_can( 'edit_posts' ) ) {
   $num = "<a href='edit.php?post_type=$post_type->name'>$num</a>";
   $text = "<a href='edit.php?post_type=$post_type->name'>$text</a>";
  }
  echo '<tr><td class="first b b-' . $post_type->name . '">' . $num . '</td>';
  echo '<td class="t ' . $post_type->name . '">' . $text . '</td></tr>';
 }
 $taxonomies = get_taxonomies( $args , $output , $operator ); 
 foreach( $taxonomies as $taxonomy ) {
  $num_terms  = wp_count_terms( $taxonomy->name );
  $num = number_format_i18n( $num_terms );
  $text = _n( $taxonomy->labels->singular_name, $taxonomy->labels->name , intval( $num_terms ));
  if ( current_user_can( 'manage_categories' ) ) {
   $num = "<a href='edit-tags.php?taxonomy=$taxonomy->name'>$num</a>";
   $text = "<a href='edit-tags.php?taxonomy=$taxonomy->name'>$text</a>";
  }
  echo '<tr><td class="first b b-' . $taxonomy->name . '">' . $num . '</td>';
  echo '<td class="t ' . $taxonomy->name . '">' . $text . '</td></tr>';
 }
}
add_action( 'right_now_content_table_end' , 'wph_right_now_content_table_end' );

custom_login_logo.php

<?php
// CUSTOM ADMIN LOGIN HEADER LOGO
   function my_custom_login_logo() {
    echo '<style type="text/css"> h1 a { background-image:url('.get_bloginfo('template_directory').'/images/your-logo-image.png) !important; } </style>';
   }
   add_action('login_head', 'my_custom_login_logo');


// CUSTOM ADMIN LOGIN HEADER LINK & ALT TEXT
   function change_wp_login_url() {
    echo bloginfo('url');  // OR ECHO YOUR OWN URL
   }
   function change_wp_login_title() {
    echo get_option('blogname'); // OR ECHO YOUR OWN ALT TEXT
   }
   add_filter('login_headerurl', 'change_wp_login_url');
   add_filter('login_headertitle', 'change_wp_login_title');

custom_user_profile_fields.php

<?php
// Remove default fields contact info user profile and replace them with something more usable

function update_contact_methods( $contactmethods ) {

  // Remove annoying and unwanted default fields  
  unset($contactmethods['aim']);  
  unset($contactmethods['jabber']);  
  unset($contactmethods['yim']);  

  // Add new fields  
  $contactmethods['phone'] = 'Phone';  
  $contactmethods['mobile'] = 'Mobile';  
  $contactmethods['address'] = 'Address';  

  return $contactmethods;
}
add_filter('user_contactmethods','update_contact_methods');
/**
To display custom fields you can use one of the two methods listed below.

// Option 1:
the_author_meta('facebook', $current_author->ID)

// Option 2:
<?php $current_author = get_userdata(get_query_var('author')); ?>
<p><a href="<?php echo esc_url($current_author->contact_phone_office);?>" title="office_phone"> Office Phone</a></p>

**/

disable_rss_feeds.php

<?php
function fb_disable_feed() {
wp_die( __('No feed available,please visit our <a href="'. get_bloginfo('url') .'">homepage</a>!') );
}

add_action('do_feed', 'fb_disable_feed', 1);
add_action('do_feed_rdf', 'fb_disable_feed', 1);
add_action('do_feed_rss', 'fb_disable_feed', 1);
add_action('do_feed_rss2', 'fb_disable_feed', 1);
add_action('do_feed_atom', 'fb_disable_feed', 1);

enable_hidden_settings.php

<?php
/**
Enable Hidden Admin Feature displaying ALL Site Settings
**/

// CUSTOM ADMIN MENU LINK FOR ALL SETTINGS
function all_settings_link() {
    add_options_page(__('All Settings'), __('All Settings'), 'administrator', 'options.php');
}

add_action('admin_menu', 'all_settings_link');

jquery_from_google_cdn.php

<?php
// even more smart jquery inclusion :)
add_action( 'init', 'jquery_register' );

// register from google and for footer
function jquery_register() {

if ( !is_admin() ) {

    wp_deregister_script( 'jquery' );
    wp_register_script( 'jquery', ( 'https://ajax.googleapis.com/ajax/libs/jquery/1.5.1/jquery.min.js' ), false, null, true );
    wp_enqueue_script( 'jquery' );
}
}

limit_number_of_revisions.php

<?php
/**
 * Set the post revisions unless the constant was set in wp-config.php
 * Default is infinite, this will set it to only remember last 5 edits:
 */
if (!defined('WP_POST_REVISIONS')) define('WP_POST_REVISIONS', 5);

restrict_admin_menu.php

<?php
/**
Restrict ADMIN menu items based on username, replace username with an actual user's name.
**/
function remove_menus()
{
    global $menu;
    global $current_user;
    get_currentuserinfo();

    if($current_user->user_login == 'username')
    {
        $restricted = array(__('Posts'),
                            __('Media'),
                            __('Links'),
                            __('Pages'),
                            __('Comments'),
                            __('Appearance'),
                            __('Plugins'),
                            __('Users'),
                            __('Tools'),
                            __('Settings')
        );
        end ($menu);
        while (prev($menu)){
            $value = explode(' ',$menu[key($menu)][0]);
            if(in_array($value[0] != NULL?$value[0]:"" , $restricted)){unset($menu[key($menu)]);}
        }// end while

    }// end if
}
add_action('admin_menu', 'remove_menus');

romove_update_for_users.php

<?php
// REMOVE THE WORDPRESS UPDATE NOTIFICATION FOR ALL USERS EXCEPT SYSADMIN
global $user_login;
get_currentuserinfo();
if (!current_user_can('update_plugins')) { // checks to see if current user can update plugins 
    add_action( 'init', create_function( '$a', "remove_action( 'init', 'wp_version_check' );" ), 2 );
    add_filter( 'pre_option_update_core', create_function( '$a', "return null;" ) );
}

search_custom_post_types.php

<?php
// MAKE CUSTOM POST TYPES SEARCHABLE
function searchAll( $query ) {
 if ( $query->is_search ) { $query->set( 'post_type', array( 'site','plugin', 'theme','person' )); } 
 return $query;
}
add_filter( 'the_search_query', 'searchAll' );

from http://wordpress.stackexchange.com/questions/1567/best-collection-of-code-for-your-functions-php-file