I think the ability to add custom tags to the files you have found using AnyTXT would be beneficial. I see this being helpful in areas where I want to mark the file for use later but even thought I spent time in AnyTXT looking everything up, I have to repeat the process if I need those files again. You could use the custom tags to extend some of the search ability or add further functions to add historical look ups for files you have searched in the past. Maybe automate it somewhat and all of the files that you find AND you open (both must be true since the tag could be written on the opening of the file) get the query you used automatically tagged to the file and then the drop down can show those queries.
No matter what though, I do want you to know that I love this product. You really do have something special here that I hope that the development never stops on.