I've been a huge fan of Duke Nukem 3D ever since I was a kid, and used to be very involved in the modding community both making and collecting mods. As such, I've amassed a very large collection of mods over the years, and since no mod manager existed (to the extent of my knowledge), I had decided to make my own back in 2008-2009. I never ended up adding half of the features I had initially hoped to implement in the project until recently since I resumed work on and completely re-designed the project from the ground up.
The Duke Nukem 3D Mod Manager is written in C++ and features Qt's core library with little to no platform specific code. It is still a work-in-progress, and has recently undergone a drastic rework which included a lot of code re-writes and tons of new features being added. There is no officially functional release yet, but I think I should be able to make one available fairly soon.
This project also largely ties into my massive mod collection which is now available over in the mods section, click here to check it out! I've been hard at work developing a dynamically generated webpage with TONS of information in PHP to make browsing / searching through my Duke 3D mod collection easier!
Current features of the mod manager include the following: