You shouldn't normally see anything of the site as the size is set to 0 in the iframe. You'd only know it's there if you look at the source for the page or if you have something like Adblock that can show you things it's blocking.
It may be doing nothing more than racking up hits for the 2345 site or collecting ip info as mentioned above. Nothing more malicious seems to be emanating from it at the moment (though it's never a good thing if people are collecting your ip addresses!)
By clicking on the User Name, you will requery the forum for that user. You will see everything that he or she has posted with that Mudcat name.
By clicking on the Thread Name, you will be sent to the Forum on that thread as if you selected it from the main Mudcat Forum page.
* Click on the linked number with * to view the thread split into pages (click "d" for chronologically descending).
By clicking on the Subject, you will also go to the thread as if you selected it from the original Forum page, but also go directly to that particular message.
By clicking on the Date (Posted), you will dig out every message posted that day.
sj