How to show editable location bar in nautilus

From Ubuntu 10.04 the location bar is displayed by default in "breadcrumbs mode". Clicking on breadcrumbs buttons does not more switch the location bar in the edit mode.
This can be done using the shortcut CTRL+L (or from the menù Go > Location).
With ESC is possible to go back to the breadcrumbs mode.

Rar files support in Ubuntu's Archive Manager

By default Ubuntu's Archive Manager doesn't support opening files in rar format. The unrar package provides this functionality, it can be installed with the command

sudo apt-get install unrar

Java plugin per Firefox su Ubuntu

To execute applets in your Firefox browser you have to install the java plugin.

Follow this steps:
1) sudo apt-get install sun-java6-jdk
2) ln -s /usr/lib/jvm/__JDK-VERSION__/jre/plugin/i386/ns7/libjavaplugin_oji.so /home/__USER__/.mozilla/plugins/

Why hibernation doesn't work?

In my case the answer is easy: not enough space in the swap partition.
In order to hibernate the pc, Ubuntu copies the ram to the swap partition, so this must be at least as bigger as the installed ram.

You can verify ram and swap size with:

cat /proc/meminfo | grep SwapTotal; cat /proc/meminfo | grep MemTotal