I want to make a cemetech viewer for gCn (going to cemetech on gossamer dosen't work).
I will work on this when I understand the protocol better.

I was going to name this hub Forum(s)Hub.
My idea for a protocol was
CALC -> ForumHub: (Type) (Extra)

Type could be 0 for reading a post, 1 for going to new posts, 2 for writing a post, and 3 for editing a post.
Also as a reply FF would be acknoledgement.
If you are reading a post then here's how I imagine it would go:
CALC -> ForumHub: 00(Thread ID)(Post on that thread #)
ForumHub -> CALC: FF(Size of that post)
CALC -> ForumHub: FF if enough space or 00 if not enough space.
ForumHub -> CALC: FF(Data)00
CALC -> ForumHub: FF

For writing a post, lets assume the calc has saved the user's username and encrypted password.
CALC -> ForumHub: 02(ThreadID)
ForumHub -> CALC: If the thread can still be written to then FF else 00
CALC -> ForumHub: FF(Username)00(Password)00(Data)00
ForumHub -> CALC: FF

I don't know 1 and 3 yet but I have thought more in depth of displaying bbcode.
1) All text will be turned lowercase except:
1.1) Bold text will be all upercase
1.2) Code text will be inverted and retain it's original case.
2) Code and the cross out thing will have bytes that tell the on calc displayer to either invert or bitwise-or with '-' all characters untill the next of that byte.
3) As you can see in 2, code will be inverted text.

This looks interesting.
I have been wondering about something like this for a while, I take it there will be no image support? 🙂

Yeah, prolly no images.

The Web bridge is down at the moment, unfortunately; since no one actively uses them, maintaining the uptime of the CALCnet bridges (Gossamer [web], Sandpaper [files], Chat! [IRC]) has not been a priority.

Once possible approach you could take, rather than inventing a new protocol, could be building a replacement bridge that speaks the same protocol that Gossamer understands.