Getting Hits from a Strange Site… any ideas?

Hi all,
For the past two days my website has been getting hits from the following address:
peakhourtraffic.com/auto4credits.php
I’m not sure what peakhourtraffic is, but it looks like something that pays people to click links? Nearly all of the hits have been bounces. In fact, there’s a few IP’s that have been ‘logged’ into my site for 8+ hours, and it looks like someone’s clicking on my main page every hour or two.
Any ideas? As long as these aren’t PPC (and don’t have to do with my AdWords campaign) I guess they’re harmless. I just don’t understand it.
Thanks in advance.

See original post by Vozzek