I’ve been playing about with WordPress plugins all day, and have created (more like stolen and modified a small amount) Tidy Slugs.
This plugin tries to catch a few of the random stuff that WordPress misses when I make the post slug.
For example if my post title was:
Ryan's Tidy Slugs, WordPress would make a URL of blog.artesea.co.uk/2007/11/ryans-tidy-slugs.html
however if it was:
Ryan’s Tidy Slugs (notice how the apostrophe is slightly more curvy) it would be blog.artesea.co.uk/2007/11/ryan%e2%80%99s-tidy-slugs.html
Very, very ugly!
(OK, you might not be able to spot the difference as WordPress loves to curve the apostrophes, however try creating a post title using the second one).