I think I can help a bit...
Ikonboard is free, and available here...
http://www.ikonboard.com/
phpBB is available here...
http://www.phpbb.com/
YaBB is Perl based, or at least it was... you can check out that forum here...
http://www.yabbforum.com/
YabbSE uses a database backend, a SQL backend... I used it and liked it quite a bit, but sadly it no longer exists... the staff went to make Simple Machines Forum... haven't used it, but you can check that out at the following site...
http://www.simplemachines.org/
Here is an option that allows you to find other programs to use on your server... Free and pay scripts are here...
http://cgi.resourceindex.com/
Perl and PHP can be added to your server easily and for free by downloading appropriate software (search Google for that).
If you want a private journal for friends and family, to keep in contact, you can also try Live Journal. You can run the software on your server or use Live Journal's server...
The software ::
http://www.livejournal.org/
The server ::
http://www.livejournal.com/
You don't have to run this on your own server, by the way, since places like Yahoo Groups and MSN Groups allow families to collaborate. However, if you use one of those services, it isn't quite as fun (since you don't have the fun of getting it working!
).
I hope all those links were helpful. One thing to keep in mind is that it is tremendously hard to get members to your forum and to keep them active. It is more likely that they will never post any new messages and never check the forum because no new messages are being posted! As long as you can keep participation up, you should be fine with your forum. Do keep in mind that participation, not specifically software, is your largest issue. Once that is in mind, you can play around with different software all you want and have fun with running your forum.
I have tried to run a forum and I have failed, lack of interest and participation was my issues. It was a pity that it failed too, since it was quite a bit of fun to run. I wish you the best of luck with your forum and hope that you have success and fun with it!
<EDIT>
You can add Perl to your server by going to this website and downloading the appropriate files...
http://www.perl.com/
You can add PHP by going here and downloading the appropriate files...
http://www.php.net/
Both sites will help you out in installing those programs. Once again, best of luck.
<edit 2>
Note that both PHP and Perl are ways of running CGI programs. CGI programs can be wrote in a variety of languages, PHP and Perl included, but you must have the appropriate interpriters to understand those languages. I am not sure what can be natively understood... I am not a tremendous web expert... but the general idea is that you need those packages in order to use other programs...
Also note that you need to pick up a database program (SQL) and that some of those are free.... ok ok, enough ranting from me...
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