Is there any information other than a password that would be considered a security threat?

I am primarily interested in knowing what could compromise the security of a server, rather than the security of intellectual property.

For example, it seems to me that it would be a security threat to include both my username and domainname.

If I post a large amount of output, it is not possible for me to know what nefarious uses it could be put to, especially if data were combined from across multiple posts.