Let your friends use pastebin service hosted by you.
This is an plain text pastebin service with access rights management. You can set access for public users: allow/disallow them to read or post something. You have also two users with permanent rights: an unpriveleged, who can only read and an priveleged, who can read and write. As service provider you can manage the rights for public and set passwords for priveleged and unpriveleged users. If you take a look a little bit closer at the service - you will notice that all necessary information like passwords is containing in URLs, which you can easily share. The advantage is that your friends have only to click on link you sent them over IM or E-Mail and start posting/reading, so they do not have to care about passwords at all.
Version 1.5: Added syntax highlighting. Small fixes. Version 1.4: Fixed tab chars (were represented by %09). Fixed commit date of postings (was timestamp, now readable dates). Version 1.3: Fixed trimming of white spaces on "Link to this posting" page. Several small fixes. Version 1.2: Fixed trimming of white spaces at the beginning of a line Version 1.1: Added the login box and description on public page. Version 1.0: Initial release.