An option to set a priority number to each item in the download queue (1-5). The user would set a default priority for freshly added nzbs. Low priority items would stay at the bottom of the queue, highest would stay at the top and be downloaded first. Priority could be automated by searching for certain words in the name, eg. 'some show' = priority 1.
I'm always moving big downloads to the bottom of the queue so I can download small new stuff. I'd really find this feature useful.