ajayver

This plugin forces vk.com to use the first image from post while sharing a link. If there is no image in post or if it is front page, the defaut image will be used, which can be set up on plugin’s settings page.

VK Image

Forces vk.com to use the first image from post while sharing a link.

igrp

VK Lock make is possible to restrict page\post access to authorized VKontakte group members only. 
Plugin will take care about site visitor authorization in VKontakte and checking if he\she is member of VKontakte group specified by you. 
Access to the protected page\post content will be allowed only if user is authorized and is a group member.
Restriction works for password protected pages\posts only – this means that your have to set page\post type to “password protected” and specify any password (plugin does not use this password, if you like you can access protected page with that password via conditional password access form, provided by WordPress).
Plugin works via VKontakte API (https://oauth.vk.com/authorize) therefore you need to make some proper (its very easy) settings at VK.COM side. See Installation instructions.
This plugin may not work properly with PHP versions earlier than PHP 5.2

VK Lock

Restrict page\post access to authorized VKontakte group members only.

VK Image vs VK Lock