Once, I wanted to clean up lots of questions (meta: Cleaning the Prototype tag).
For this purpose, I made the following script: http://userscripts.org/scripts/show/121541, where you can find out what the tool does:
Tag overview
By default, a confirmation dialog appears when attempting to submit a tag edit.
By default, the question summaries at the tag overview page (containing questions) of an ambiguous tag will not expand.
A button is added at the upperleft corner of a question overview page. This button can be used to open multiple questions at once, without having to click at the separate links.
Question page
At a question page, some buttons will show up. It's possible to retag the questions by clicking once at the button.
Anything which was prefixed by "By default" can be customised by editing variables at the source code.
At all times, the page adjustments can be toggled by pressing SHIFT + ESC
Emphasis: Do not just retag the questions, also fix other problems in the post when possible!