Some sort of wiki, like trac. It has support for code highlighting. It's easy for others to look at later.
You could just use Skype but turn off the emoticons (Options->Chats & SMS->Chat Appearance->Show Emoticons). It will not disrupt your formatting and if worse come to worse you could always just send the whole file. Some other IM clients offer this functionality as well but with mixed results. I would assume that tools like Miranda IM would allow you to turn off the emoticons and adjust the font to use a monospace one.
Alternatively you could use Wiki but it's some extra work and I would only advise it if the snippet has any particular value.
although you have must likely thought of this but is it not possible to have a shared folder that you can all access and then be able to open the document in your preferred editor
or maybe look at a web based project management where you can all login in and share resources?
Jeremy Cantrell's response led me (via google) to the Wikipedia page on collaborative real-time editors.
This is where you can find a comprehensive list of software products that serve the required purpose, along with some interesting explanations of the technical difficulties for implementing such software.
collabedit is a browser based collaborative source code editor.
Here's a demo http://collabedit.com/display?id=46786.