I think the first user block (4th box when one is logged in) should also (by
default) have a list of own issues which were created by the user.
Actually I assumed that "Your issues" was just that, but it turned out that it
showed issues that were assigned to me.

I can actually change the semantics of "your issues", since I agree with your
intuition that it should mean "issues I have created".

Will do.
-- 
Greetings, 
A. Huillet

"Your issues" now lists the issues you have created. There is no default link to
get the list of issues you are assigned (I've replaced it). I guess someone will
ask me to add a "Issues assigned to you" link? Unfortunately the label is too
long and will distort the left side box... better suggestions?

"Your Assignments"
I can't think of any individual reasonably mistaking this as something else.

You could even replace it with "Your To-Do" (to keep it in the vein of "Your 
*"), though I'd stay away from "Assigned Issues" and the like because it could 
be misinterpreted as, "Things currently being worked on," not necessarily what 
*you* should be working on.

"Your todo" feels good.
The thing is - I don't use those links myself. I've set up two custom searches,
one called "latest" that sorts all issues by last activity regardless of their
status, and one called "open" which shows all open issues sorted by priority.
You can setup custom filters in Roundup so I'm not sure it's useful at all to
provide pre-made filters. :)