This userscript applies to metal-archives.com(Metal Archives), in discography pages.

It splits the 'Reviews' column into 'Reviews' and 'Ratings' and makes the tables in all discography tabs sortable
(just click on each of the table headers).
Tip: you can sort multiple columns simultaneously by holding down the Shift key and clicking a 2nd, 3rd or even 4th column header.
(Note: since version 2.0 the visual glitch/delay that occured as you switched sub-tabs (tables) appears no more)
Since version 2.1.0 added Search filter (mouseover below a column header to reveal the search input, case insensitive).

Example (see screenshots below) :
http://www.metal-archives.com/bands/Kamelot/166 (DISCOGRAPHY > MAIN tab)
-the script works in all DISCOGRAPHY tabs-

Tested with Greasemonkey and Tampermonkey.

This userscript makes use of:

• jQuery 1.11.1,
• the jQuery plugin tablesorter (forked by Mottie), and
• the JavaScript library Mutation Summary (by Rafael Weinstein).

Thanks a lot to Rob Garrison, Brock Adams and Mottie for their invaluable help (1, 2, 3, 4)

Screenshots: