Eh, couldn't think of a better place to shove this. If I (or someone else) thinks of one later on, might move it there instead.

For now, think of it as a bonus for loyal TWim'ers!
Anywho, spent a couple o' hours writing a Greasemonkey script which'll (upon loading a forum page) go through all the posts, all the images in the posts and if the image doesn't fit on the page, it'll be resized down to so it can fit. Clicking on the image will restore it to its original size, clicking again will shrink it back to fit. (If you run into people who link large images in [url] tags, blame
them.)
Few things to note, it won't re-check the sizes if you happen to resize your browser window. It'll just use the sizes of when you loaded the page. Also, it's probably not as well coded as it could be, but as it is now, it works. At least on Firefox 14.0.1. Please do let me know if it works/doesn't elsewhere or if you have ideas for improving it.
Things you'll need to make it happen:
If you use Mozilla Firefox, the
Greasemonkey extension
If any other browser, can't say. They probably have it (or similar) in some shape, way or form.

The script: Download/install