I just want to mention some things which, for me, are not very logical.
In the sidepanel, there are a couple of links. If you are not logged in, you can always see: Categories, Recent Discussions and Activity.
When you hit the first 2, the sidepanel stays intact. You can easily hit another link. But when you choose the third one, Activity, the sidebar is gone. You have to browse back for the sidepanel. So i can imagin when people click on activity they think: "Hey, where is the sidebar gone?"
The same behaviour occurs when you click on a member.
Now you can see again a sidebar with: activity, discussions, comments and on this forum: addons.
When clicking on the first 3, the sidebar is still there. When you click on addons, the sidebar is gone. So again you have to browse back. I know that the last one is a plugin, but it would be more consequent if the sidebar on the addons page also keeps intact.