I started on this but ran out of time after I hit a snag. However, you should be able to download all the packages using apt-mirror and then copy the .deb files to a single location and create your own repository from those. There's a repository howto here.

As long as you copy the .deb files you can use apt-mirror to refresh the packages without having to download them all again.

One thing I found is that you may have package version conflicts between mirrored repositories. The other was that I could connect to the new web repository I created, download the package but it didn't install for some reason. I'm sure it's because I didn't have the repository setup quite right.

On a related note if any developers are reading, would it be realistic to have a central repository where developers or maintainers could upload packages to an incoming location and have a process pick it up, validate and add it automatically? I could even see this being tied to the application database similar to the way debian does with their packages. That way you select your application from a single repository and shouldn't need to add in 15-20 repositories to get what you want.

Interestingly enough, I don't see any information in the maemo database that isn't already stored in a package. Building the database from the repository seems like the logical way to do it and not building a database from multiple repositories and relying on someone to manully keep them in sync.