I've just published a new project on GitHub, named znc-log-viewer, that might be useful for IRC junkies.
Searching those log files have always been a hassle, because they are located deep inside the .znc directory, and there are a lot of files stored in one big directory, which makes it hard to get an overview when you want to pull out your trusty friend, grep.
If you actually bothered to use grep, you would also notice that a single log file has a lot of server messages in it, that is generally not interesting when you're trying to figure out what has happened since the last time you were online. In my case, I just want access to the conversations that have been going on.
So if this problem is something you can relate to, feel free try out my new tool. If you find any problems with it, please open up an issue on the GitHub page.