http://drupal.org/project/dreditor
Using Dreditor to Review Patches
All the professionals and cool kids (well, a lot of them) use a Greasemonkey script called Dreditor to perform patch reviews. Dreditor stands for Drupal editor and is script that turns your Firefox or Chrome browser into a patch reviewing machine. Created by Drupal angel Daniel Kudwein (sun), it is available at drupal.org/project/dreditor.
To use Dreditor simply highlight a part of code we want to comment on, type our comment in the box that appears on the left, and click save.
Until you click Cancel, Dreditor assumes that you are you still are viewing the patch. If you try to review another patch by clicking Review, Dreditor doesn't bring up the new patch you want to review instead you continue editing the first patch.