Acpiw (short for ACPI watch) displays the content of /proc/acpi (where the Linux ACPI system reveals a lot of information) and records changes in the files there. You might use it
I originally wrote it to learn about Linux' ACPI system, but since then found it useful to explore the ACPI capabilities of different computers. acpiw makes very few assumptions about the content of /proc/acpi. It has a text mode interface, useful mainly for documentation purposes, and a Gtk+ interface.
Just to give you a basic idea:
The tree on the left consists of directories ("thermal_zone"), containing files like "temperature" (or other directories), containing entries ("temperature:"). An entry is one line in a file.
Red entries (or, in the case of directories, some entries in some files in this directory) have changed since the start of the program -- just let acpiw run for some minutes, and you will have an idea what is changing and what is constant in /proc/acpi).
Blue entries are writeable.
In the right part of the window, you see the history of the entry that is selected in the tree.