I'm covered when it comes to music, since [pretty much any music player/library manager] allows me to quickly find songs by interpreter, album, genre... For everything else, all I have is a series of hierarchical folder structures, but hierarchies have limitations. I can find Blade Runner easily, but what if I wanted all of Scott Ridley's films? Where is "Good Omens", in the Terry Pratchett folder or in Neil Gaiman's? Furthermore, in a collection with hundreds of similar items, it would help to have some extra clues such as covers (for comic books) or synopsis for TV shows' episodes.
Do you have any software to help you handle digital media libraries? Specialized software (say, something that only work for comics, something else for movies), or generic media libraries? Opensource alternatives are preferred, but commercial software is fine as well.