Most recent one is a bug in lubuntu based on 16.04 where the mouse cursor disappears after system goes to sleep (but is still functional).

Workaround is ctrl-alt-f7 to switch to console then ctrl-alt-f1 to switch back to GUI, and the mouse cursor reappears.

https://bugs.launchpad.net/ubuntu/+bug/1573454

Another one is a sweet widget in OS X called iStatPro, which was no longer working ias of Mountain Lion. But, there is this workaround which for me still works on El Capitan: http://hints.binaryage.com/istat-pro-for-mountain-lion/