Notices

What are the packages providing a clock that is not covered by windows (so either in the status bar or on the left) and that takes minimal space (basically, no additional space)?

I've heard of Statusbar Clock, but it takes space in the status bar, and this is a problem when it becomes full. There's osso-statusbar-cpu which gives a clock for free when one wants to display the load average and memory, but it is redundant with LoadApplet and the clock isn't very visible.

I think that the best place would be over the Application Switcher icon, since the icons on the left are larger than those of the status bar and the Application Switcher icon doesn't provide any information. Would this be possible?

Those and Large Statusbar Clock are your only current options.
You do know you can change the order of icons on the Statusbar? I have mine set so the clock is always on the far right in the status bar and the less important Icons (Auto-Update, Bluetooth, GPS) will pop into the "Second Statusbar" dropdown as they appear (the little circle with an arrow).

If the status bar gets over full, it's easy to see the next row when you need it. I don't know about you, but I don't always want all that information.

I'd like to avoid the second statusbar if possible.