Well, maybe unfilter is the wrong term. What I am wishing for is the ability to create a set of "filters" that say "I don't want to see this type of entry". Then if I want to see everything, I turn off filters. Otherwise, I can turn off
the events that don't interest me in most cases, leaving the odd ducks for analysis.
Being able to turn off some messages about which I already know the story behind would make studying the exceptions easier.
Another useful feature would be coordinating information between the various IIS, Server, SharePoint, event, etc. logs into a master view of the system. This seems like it would make your tool even greater.
Just some ideas.