Those are web bots crawling the site.
For search engines to work they have to continuously crawl around the internet and *read* everything they can. They are programmed to read and follow links and such. The more sites you have linking to you, the more often the web bots are going to happen across your site. It happens to every site on the internet. Also when it says something like "Google.com is using personal messenger", it doesn't mean it's actually PMing someone, rather it just happens to be crawling the PM.php, (or PM.html, or whatever this site uses) page.
Long story short they are just programs gathering information to use in search engines.