Here's my plan for restructuring contrib area very soon:
1) Create a new tree structure there that exactly mirrors the structure of plugins in moodle itself:
2) Move all the existing code into this new structure. I know this will break a lot of links and possibly CVS setups, but I think it's worth it to have a nice easy-to-understand structure going forward.
3) Create branches called MOODLE_15_STABLE, MOODLE_16_STABLE and MOODLE_17_STABLE which developers can use if they wish to support separate versions..
4) Fix download.moodle.org so that it packages and stores modules in a way that mirrors the tree structure.
5) Edit Moodle Modules listing and fix all download links in there.
6) Document, advertise, explain to developers.