g1smd - 4:46 pm on Apr 1, 2010 (gmt 0)
Have you got just one of these or a whole bunch?
I worked on a site last year that had lots of duff incoming links with extraneous spaces and punctuation in the URL.
For that, we created a landing page and then simply redirected any URL request with a space, bracket, comma, or % sign in it to that page - the worry being malicious incoming 'bad' links with 'bad' words in them that we might otherwise have 'corrected' to point at a real content page, and hence associate it with the unwanted 'bad' words.
We sacrificed the unindexed landing page for that. That page had links to major site sections, a few featured products, a button to report linking problems, and so on.
WebmasterTools was also great for finding duff incoming links from other sites. Do make sure you check both the www and non-www WMT reports for your site.