Yes, very impressive. This means over 1000 different IP addresses accessed the website in a space of 30mins.
I think it must have been some automated robot requesting loads of pages, but can't be sure.
I do know that around my birthday numbers go high, I think that is because my signature in on other forums with a link to the website, and perhaps when my birthday is announce on those forums people follow the link to our website. I cant be sure of that one, but it may make sense.
So its certainly worth popping a link to this forum in your signatures on other forums, I link to a page about my car.