Very nice update to ZDL, QBasicer.
I just came across this thread yesterday and am now using this instead of ZDL 3.1a. I started out launching Doom years ago using batch files and later on windows shortcuts. What I like about ZDL is it is a clean browse-and-add interface to essentially make batch files (.zdl saves) without all the clunk involved writing them with notepad or editing a shortcut.
The resizable windows are great - ZDL 3.1a runs in a window the size of a postage stamp on my Win7 netbook.
Can't think of much else needing to be added - for me I have different directories for addon effects such as dehacked, decorate, music as well as my pwads and iwads. I also save all my .zdl files to one directory as well. Maybe be able to specify directories to start the browser window in for different types of addons via buttons for the external files pane (dehacked, effects, pwad, music) and a directory for .zdl files. Either way this should be strictly optional as I'm quite happy with the program as is - no need to bloat it simply to have updates to announce or clutter the interface.