A config thing in the GUI to set your ID would be nice.

And as far as packaging goes, why not upload to KDE-Apps.org so we can grab it with Get Hot New Stuff on the Plasmoid picker?

EDIT:

I tried putting in my ID for ubuntu.stackexchange.com into lib/settings.py and s/stackoverflow/ubuntu.stackexchange/ on lib/stacktray.py but the text hover only ever says "Text" and I get 

    Traceback (most recent call last):
      File "/home/maco/code/StackTray/lib/systemtray.py", line 71, in run
        "You have %d reputation!" % self.rep, msecs=5000)
    TypeError: %d format: a number is required, not NoneType

On the shell