Save this search string into a simple text file and paste it into the search box. This method will allow you to easily search the archive every month. Another way to use newsgroups is by including your surnames in your signature block. So only one line remains for surnames. Rotating the surnames can get them all in, at least occasionally.
Rare surnames are also a good choice.
Again, common surnames should have date and location information included. However, if you like to participate in these groups, creating a surname listing is fairly easy. Of course, listings are software-dependant. In some chat rooms, participants use them as a way of introduction. Just ask for help for your particular software.