SideBar is easy to make. Just few edits in Index template 
I proposing change Mention plugin with more popular and less buggier DVZ Mentions (https://community.mybb.com/mods.php?action=view&pid=29).
My plugins proposition:
mmybb (https://community.mybb.com/mods.php?action=view&pid=637) - Creates Mobile-Friendly Standard Theme for mobile users.
DEMO: http://mmybb18.flexplat.com
Automention (https://community.mybb.com/mods.php?action=view&pid=558) - Autocomplete Mention. Working wth DVZ Mention and DVZ Shoutbox.
DVZ Random Avatars (https://community.mybb.com/mods.php?action=view&pid=378) - Sets Random Generated Geometrical Avatar for Non-Avatar Users.
MyProfile (https://community.mybb.com/mods.php?action=view&pid=198) - Enhances MyBB's default users profiles with comments, friend system and last visitors.
ABP Imgur (https://community.mybb.com/mods.php?action=view&pid=386) - adds a drag & drop zone in the new post and full edit interface. You can add one or more pictures simultaneously , they are uploaded and the corresponding MyCode is inserted in the message.
I proposing change Mention plugin with more popular and less buggier DVZ Mentions (https://community.mybb.com/mods.php?action=view&pid=29).
My plugins proposition:
mmybb (https://community.mybb.com/mods.php?action=view&pid=637) - Creates Mobile-Friendly Standard Theme for mobile users.
DEMO: http://mmybb18.flexplat.com
Automention (https://community.mybb.com/mods.php?action=view&pid=558) - Autocomplete Mention. Working wth DVZ Mention and DVZ Shoutbox.
DVZ Random Avatars (https://community.mybb.com/mods.php?action=view&pid=378) - Sets Random Generated Geometrical Avatar for Non-Avatar Users.
MyProfile (https://community.mybb.com/mods.php?action=view&pid=198) - Enhances MyBB's default users profiles with comments, friend system and last visitors.
ABP Imgur (https://community.mybb.com/mods.php?action=view&pid=386) - adds a drag & drop zone in the new post and full edit interface. You can add one or more pictures simultaneously , they are uploaded and the corresponding MyCode is inserted in the message.