Bob, suggestions are a form of feedback, so you are in the right spot! I really appreciate feedback in all of its forms, and will do what I can to accommodate requests and suggestions.
I chose this forum application among a plethora of applications. This one doesn't have all the "bells and whistles" that many of the other popular forum programs do, but it is very fast, small, efficient, and user friendly. I needed something that wouldn't bog down my server as the forum becomes more and more popular.
Regarding your suggestion, here are a few things you can do:
1) At the top right of the index page there is a link that will "Show new posts since last visit".
http://www.nifty-stuff.com/forum/search.php?action=show_new
2) At the bottom of the index page I've setup a "Recent Topics" list. This is where I usually go when I visit the forum to see what is new.
3) Subscribe to topics: This is one of the BEST and most often used features of the forum. When you select "Subscribe to this topic" at the bottom of a forum thread you will get email notifications when someone replies to that thread. The great feature of this tool is that you only get ONE notification via email no matter how many replies have been posted to that thread. If you no longer want to get notifications you can toggle on / off this option on each thread.
I'm working on a way to get more notifications on new posts. For example, I'd like to include the option to have the "subscribe to topic" set as yes for the default whenever someone replies to a post. Another idea would be to "subscribe to category" which would send you an email whenever someone creates a new topic / thread.
Until then, I suggest you subscribe to all the topics you think are interesting or that you start so you can be notified when there is a reply!
I'll look into other solutions. If you (or anybody else) have more comments, questions, or suggestions, please send them in.