I tried to make the comma *,* bold, but no success. I tried with verbatim =,=, but no success as well.
You can achieve what you want by adding the following to your .emacs:
(setcar (nthcdr 2 org-emphasis-regexp-components) " \t\r\n\"'")
(org-set-emph-re 'org-emphasis-regexp-components org-emphasis-regexp-components)
The manual says that org-emphasis-regexp-components can be used to
fine tune what characters are allowed before and after the markup characters [...].
It is a list containing five entries. The third entry lists characters that are not allowed to immediately follow or precede markup characters. By default, , is one of them so in order to successfully apply formatting to this character we have to remove it from the list of characters disallowed before or after the markup characters. This is what the call to setcar does. The purpose of the second line is to rebuild the regular expression for emphasis based on the modified version of org-emphasis-regexp-components.
~"~ doesn't register as verbatim on the org-mode mailing listorg-emphasis-regexp-components RET