If you're using the Postalicious WordPress plugin to post your del.icio.us links to your blog, you might have noticed that it doesn't always handle the occasional 500 errors from del.icio.us very well, and you end up with a bogus 'links' entry on your blog with a link to '500 Server Error'.
In itself, it's not that big a deal; I usually notice the bogus post pretty quickly and just delete it, but, by then, it's been tweeted by Twitterfeed, pushed to Facebook, and folks have it in their RSS stream, so they hit the 'links for the day' link and get the default '404 page not found' message. In fact, if you ever delete a post for any reason, you're in the same situation - the link is out there, you can't call it back (even if you go delete it from Twitter and Facebook, it's still out there somewhere!), and people are going to land on that ugly page.
So, I got thinking... That default 404 page isn't really good for much... What if I could just send people to the main page of my blog? Well, with a couple of minutes googling I found a useful blog post on the subject and the WordPress docs for get_bloginfo(), and came up with the following replacement for the default 404 page:
<?php header("Status: 301 Moved Permanently"); header("Location: ".get_bloginfo('url')); ?>