You can check EagleGet and IDM for instance. You can start and stop a single download in a list, when I don't want to use queue's.
By default, you add various downloads to a Main Download Queue (not custom queues you create). It doesn't mean that you need to/have to start the whole queue download, when you only want to start a single download at this particular time. Simply click the start buton next to the download so that you can download just that file.
I think the confusing term is the word 'Queue'. What happened before queue's were invented? You simply transfer various downloads to an external download manager, and then if you want to start only a single download for a file at some other time, you simply press the start button next to it. As simple and easy as that. This feature is what's missing in DN.