Forcing code standards would be a bad thing indeed
An idea I have been playing with for a while: creating default images which coders could add to their threads, indicating the mod follows
specific code standards, but maybe not all (free to choose which).
A bit like the W3C icons:

Everyone can add them to their sites, but they give absolutely no guarantee.
We could create buttons like:
- Valid XHTML
- Fully templated
- Fully phrased
- vB input cleaner used
- Includes hook locations (for big mods)
- Accessibility: session url's, RTL support (left-right style variables), ...
- Admin help included
- ...
And this doesn't require any regulation from vB.org staff (only hosting the images would be nice)
Like the W3C does with the
WAI guidelines, we could also create conformance levels. If your mod matches a specific group of standards, you can use the "Level 1-2-3-..." button.