A multithreaded hyperlink checker that crawls a site and looks for 404s. Unfortunately, not maintained anymore and written in Python2. Still useful.
Give the site a link and it turns it into a totally legit, sketchy as hell link. It's the opposite of a URL shortener.
A web service which will relay clicks on a particular link to the destination without the other end's owner knowing who's doing it. Highly recommended for avoiding leaving traces in referral logs.
A URL shortening service for posting links to Twitter, identi.ca, or any other service you like. There is even an option to generate a QRcode out of a URL.
How to re-target a cloned Git repository if the master copy's URI changes for some reason.
git remote set-url origin new.git.url/here
How to change the site URL of a Wordpress install by altering wp-config.php.
A python module which lets you search the Wayback Machine at the Internet Archive for a URL and download the entire package.