I'm aware that this is indicative of bad security practices and not some vulnerability in those systems, but that didn't make it any more comfortable to see their familiar UI elements exposed in all their nakedness.
In fairness, some of the better designed servers redirect to a domain. For example, one of the IPs I stumbled redirected to this weird portal (where the links point to the parent domain)
It's also really fun to find web servers on nonstandard ports, but I worry about the site then being abused to find compromised servers.
Like this one: http://188.8.131.52