As you probably know, the Ubuntu 11.04 panel doesn't let you add applets - it's not that panel is locked like it was in Ubuntu 10.04 Netbook Edition, it simply doesn't support applets (it doesn't have such a feature) as the top Unity panel is not a Gnome panel.
However, if you have a Gnome panel applet that you just can live without (like CPU Frequency Scaling Monitor which you can see in my screenshot or Jupiter which is a must for a netbook), you can use a simple "hack" to use it: simply open a terminal and type:
gnome-panel
If you want it to start each time your computer boots, simply add it to your Startup Applications.
This should make both the top and bottom Gnome panels show up - you can delete one of them and/or move them wherever you want (top, bottom, right) and further tweak them so they don't interfere with the way Unity looks/behaves.
In my screenshot I've only kept the top panel which is set to autohide and "Expand" is unchecked. That means that my panel (which only holds one applet) will automatically hide and it will only take a few pixels of the top Unity panel when I need it.
Using a Gnome panel also means you'll get the ALT + F2 Run dialog back (nothing happens when you press ALT + F2 in the default Unity setup).
This should make both the top and bottom Gnome panels show up - you can delete one of them and/or move them wherever you want (top, bottom, right) and further tweak them so they don't interfere with the way Unity looks/behaves.
In my screenshot I've only kept the top panel which is set to autohide and "Expand" is unchecked. That means that my panel (which only holds one applet) will automatically hide and it will only take a few pixels of the top Unity panel when I need it.
Using a Gnome panel also means you'll get the ALT + F2 Run dialog back (nothing happens when you press ALT + F2 in the default Unity setup).
Idea thanks to garvinrick4 @ Ubuntuforums.