This add-on allows the administrator to set certain user groups for their as join-able. Users can then select which user groups they would like to join.

Features:

• Admin can set joinable usergroup on registration
• Admin can make usergroup optional on registration and for forced user to chose at least one
• Moderators can be assigned to user groups
• Moderators can also view a list of all users in their assigned group
• Admin can set different custom fields as required when user will create a request for join user group

Note :
Please send me PM if anyone need this addon or also i can add any other feature on it