A full blown mod database rather than a forum implementation would offer a lot of advantages.
Eric's favorite example is Garrysmod.org, and this would act as a neat merger. The actual mod display could be basically just a topic; it depends on how uploading works, exactly.
Commenting and posting are, and should be, basically the same thing, in regards to mods, so there's no
difference with the two setups. Also, having an actual mod manager rather than just a bunch of disconnected attachments really helps to keep things organized.
I do realize, however, that this might have problems if someone wanted one topic with multiple mods. Other users posting things into a thread might also encounter problems, but that should be solvable with a PM. Obviously, it's not a perfect solution, but god knows that the current system isn't either.
THIS IS NOT ACTUALLY AN EDIT BUT WAS STILL TYPED WELL AFTER THE PRECEDING POST:
not perfect, but seeing something like that (followed by mostly-regular posts, though ideally without avatars and signatures, just text and usernames) would really help, in my opinion, with basic mod integration. As I mentioned in the box, I'm not sure what to do with the lower left box, though tag integration sounds like it could go there well.
Stats, in the top right, would be things like the views, downloads, comments, etc, along with options to up/down vote, or a 5 star system, or whatever whoever decides.
Pictures would be stacked in whatever number they're uploaded, but they have a dedicated spot. As in, two pictures would take up the same amount of space horizontally; they'd just both be halfway from the middle outward. GIFs, if within maximum thumbnail dimension, would be shown directly; otherwise, hotlinked.
The attachment + summary on the right would basically be a station, with a titled (not strictly filename based) heading that would probably indicate version, with a small blurb (changelog, info, installation, whatever) immediately below it. That mockup doesn't give it much room; it'd probably be at least three lines of 40 or so characters. Uploading new files could happen within the same "station", meaning that you keep your old download count (this is important to some who keep track, before non-modders scoff) and replace the file within it. Or maybe not, I'm not sure on that. If it's a single mod thread, archiving older versions might be good, but that would probably require more server space. A multimod thread with each mod having a "station" would also be just jim dandy.
If anything I'm saying makes sense, please confirm that. I'm typing this up far too late, and I'm not sure of myself. If anything DOESN'T make sense, I'd be happy to elaborate.
Now, I'm not entirely sure WHY I'm doing this, but it seems like a neat idea and it should be entirely possible. Eric and James should get to it, and they might as well have a fairly good plan in place. Again, not saying this is perfect design or that I'm the perfect designer, but it'd be pretty neat.
I can also whip up a more fancy mockup for this one. A nice titlebar would be important for snap legibility, probably with just title and author info. Usability is good; "other mods by this user" and maybe even categories (rather than just tags), as in "Mod Contest 4" gives you a brief page with all the MC4 entries. I'm not sure how "other users who downloaded this liked" would work, but "similar" mods based on tags or whatever could probably be pulled off.
Anyways I had to go to sleep two hours ago.