I'm participating quite a bit in BNW development and I'm always using Dropbox to host test patches for BNW. It'd be better if those could be hosted on the site itself to prevent link rot.
My suggestion is to either enable .zip files in attachments for those who need it; it could be restricted by forum and/or role.
My other suggestion is to have a section for "extras" like unofficial patches, alternate sprites, beta patches, etc. for each mod. It could either work as
A) a file dump with upload permissions given by the mod owner, where you can just host a file and link to in a forum post, or
B) as some kind of aggregator for forum attachments, possibly using a tag system. Eg. any attachment in a BNW forum post using the tag "addon" would end up listed in this section as well, assuming the poster has permissions. The mod owner could tag posts/attachments for inclusion in this section, or give permissions to members.
I imagine it as a simple list of files, with links to the post in which they were attached, and possibly sorted using tags. The mod owner could edit this list at will to include or remove attachments.
This could also be useful for new projects that aren't established enough to get their own download in the main section. Such as if a new user came to the site and wants their mod hosted, or established user is working on a different mod.