Click Online suggested this website a couple of weeks ago about its Internet Connection Speed Test, but after briefly looking through the website, I found out about something quite shocking.
This page, http://www.internetfrog.com/mypc/browserinfo/, shows you all the details about your browser, but is also able to find out what's on your clipboard. I personally think that this level of access is highly dangerous, so if you're on dodgy websites like crack websites, I'd be careful if you have something like Credit Card details on your clipboard.
I am looking into this 'security hole' and I am trying to find something that could stop it or at least overrride it.
In the meantime, I highly suggest you go to this page to check your version of Java Runtime - a recent update was released (Update 6) because 3 very dangerous security holes have been found in the program, and, as usual, with the ability to run software on your computer remotely.