Awesome
This plug-in provides automatic closing of quotes, parenthesis, brackets, etc., besides some other related features that should make your time in insert mode a little bit easier, like syntax awareness (will not insert the closing delimiter in comments and other configurable regions), <CR> and <Space> expansions (off by default), and some more.
Most of the features can be modified or disabled permanently, using global variables, or on a FileType basis, using :autocmd.