Simple service. If your goal is to make money of the AdSense ads, you might want to think about what kind of actions you want to encourage users to take after they've checked a domain's server, in order to increase their time on your site.
One of the things I'd add is a "How do you know?" link that talks about how you can tell what kind of server the site's using.
Also, why have social bookmarking links? Why would anyone put the results on reddit? Why would anyone expect enough others would upvote it to be worth posting?
It's also not clear that the Facebook, twitter, and digg icons are links to more sharing actions; many other sites use those size of icons to link to their own profiles on Facebook, Twitter, etc.
Thanks JayNeely, I'll add the "How do you know" info page. I'll also modify the facebook, twitter icons to something on the lines of "share this link".
What extra value does this provide me over just checking the header in firebug? Firebug also gives me a lot more information than what you are providing.
In the first case, I would recommend either parsing the user input to try and return some reasonable results, or just return a more direct error message.
But they do run on different web servers. The first is a custom Arc-based web service, the latter an Apache install. What could be a more direct error message than stating plainly that the information isn't available?
How would you go about protecting the search results, say I plan to write an App Engine clone which actually url fetches results from your service and provide an ads free interface with some more features?
Is verifying the Referrer header enough for this kind of protection?
Spoofing the referrer header is trivial and so wouldn't offer any protection in this case.
I do, however, wonder if there would be any benefit to scraping the beewulf site. Retrieving and parsing the relevant headers yourself is trivial and would remove from your hypothetical clone app any dependency on beewulf.
One of the things I'd add is a "How do you know?" link that talks about how you can tell what kind of server the site's using.
Also, why have social bookmarking links? Why would anyone put the results on reddit? Why would anyone expect enough others would upvote it to be worth posting?
It's also not clear that the Facebook, twitter, and digg icons are links to more sharing actions; many other sites use those size of icons to link to their own profiles on Facebook, Twitter, etc.