vim-insert-char

Insert count of a character. Repeatable.

Usage

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
     ^ cursor

3<Space>g -->

Loremggg ipsum dolor sit amet, consectetur adipiscing elit.
       ^ cursor

Mappings

By default maps to <Space>. To change that to underscore:

let g:insert_char_no_default_mapping = 1
nmap _ <Plug>InsertChar

Source

Anonymous contributor at Vim Wikia.