Anyone using Audiocheck.net?

I was interested in a source for for audio test tones.  A quick search on-line came up with Audiocheck.net.  

Just navigating the site for the first time but it does have a sine-wave sweep with voice labeled (10Hz increment) test tones that seems like what I was looking for.  It also has a LOT of other "tests" including a blind test for evaluating 16 vs 8 bit audio quality as well as "audiology" tests to check your own hearing.  Looks very helpful AND educational. Much is accessible "free" but there are higher levels of access available for a fee, I think.  Haven't read the details yet.  Would be interested hearing from others that might have experience with the site and some of the tools there.