I'm glad you like the name. I tried to find something unique (easy to find using a search engine), but I always wondered if "Ubooquity" was not to weird to pronounce for a native speaker.

"post forwarding" was just me trying to write "port forwarding" on a mobile phone and failing.
Each device has to point to the other one in the right order. Let's says you have this setup (that's what I have myself):

PC (Ubooquity) <= Router <= ADSL Modem

Then if Ubooquity is running on 192.0.0.1:2202, your router will have to forward port 2202 to 192.0.0.1:2202, and (assuming your router IP address is 10.0.0.1), your ADSL modem will have to forward port 2202 to 10.0.0.1:2202.
(I kept the same port to keep things simple, but you can map port differently if need be)

I have no experience with NO-IP but I guess you just have to point your NO-IP alias to the port 2202 of your public IP.

I guess that if you already use Plex over the Internet, you already know all that. But I don't really know what other advice to give as Ubooquity is similar to any other server application in that matter.

If you use an ADSL modem to connect to the Internet, you probably have to configure port forwarding there too (I had to to).

Just in case it might help other people: Bo has solved the problem by switching from Raspbmc to Raspbian.

Since the next version is still weeks away, here is a patched one which solves this specific problem:
http://vaemendis.net/ubooquity/downloads/beta/Ubooquity-1.7.7.zip

Interesting, although I still don't understand why the working directory is "/root/".
Do you have other files created by Ubooquity in the "/root/" folder (like "cache", "logs", "preferences.xml"...)?

In any case this problem will be solved by this feature: http://ubooquity.userecho.com/topic/794934-when-using-duserdir-switch-a-few-oddities/.

If it appears in theme selectors, it means the new folder exists somewhere on your system.
The somewhere is supposed to be the directory from which you launched Ubooquity, but I assume you have already checked there.

Perhaps you could try to do a "find" on your whole system to locate the newly created directory ? (it has the name you gave to the new theme).

I still have no clue as to why this happens (perhaps some symlink or Linux user right combination I have not anticipated), but knowing where the new dir is created would help.

Fair enough, I'll try to implement a proper user dir switch. :)

Disclaimer: I don't know anything about Unraid, so my question might be stupid.

Assuming Ubooquity is launched through a script by the plugin, wouldn't it be possible to use a variable for the working directory that would allow the user the same flexibility as an explicit command line argument ?

Something like:

cd $MY_UBOOQUITY_WORK_DIR
...

I'am asking because using the "user.dir" setting is not a completely reliable solution (hence the bugs you encountered). So if there is a real need for a working directory setting, I'll implement it in the code itself. But I really want to be sure that this work is required as for all use cases I have been told about (except perhaps yours, hence my questions), the "cd into another dir" method was enough to solve the problem.

You're right, there is a problem with the webadmin.cred file.
I will probably fix it. However you can easily (and in a more reliable way) ensure that all files will be created in a specific directory by going into this directory before launching Ubooquity.

For instance if Ubooquity.jar is in /home/pi/apps and you want it to create its files in /home/pi/data, just "cd" into "data" before calling java:

cd /home/pi/data
java -jar /home/pi/apps/Ubooquity.jar

Much easier and safe.
Let me know if you have a use case that can not be solved this way (really curious).