more on Firefox sidebars

Incidentally, aside from the fancy extension installer method, there are two other bookmark methods to make pages load in the sidebar.

You can go into Bookmarks->Manage Bookmarks... (or just pull down the bookmark menu) then pick the one you want and right-click, select Properties, then check the box that says Load this bookmark in the sidebar, click OK.

If you want to programmatically add a bookmark from a page that will open in the sidebar, use e.g.

<a href="javascript:window.sidebar.addPanel('Sidebar Name','URL','');">install sidebar</a>

The user will get an "Add Bookmark" popup window, and whenever they click on that bookmark, it will open in the sidebar.

Info based on Mozilla Sidebar.