cyberdyne - 8:56 am on Feb 27, 2012 (gmt 0)
Wilderness, to answer your question, all my sites have custom error pages. I've always had it fairly close to the top of my to-do list at the start of any new site. I appreciate some prefer not to but I don't particularly like pages which don't aesthetically fit with the rest of a site, even if it is just an error page.
With regards to HTTack, after checking logs from prior to last month it appears it (and a few of its' cousins) have been used on a number of occasions on other my sites but all unsuccessfully due to htaccess blocks. They all now have a notification system on their error pages too.
Additionally, the owner of one of the sites where (attempted) use this type of software now appears to have been fairly frequent has requested the IP range responsible is blocked permanently - perhaps a touch of paranoia setting in but it seems they're trying to protect their investment. You'd think a new company, regardless of how similar to another their business is, would want a totally unique web site with individual content and appearance, but apparently that's not always the case.