Extension:InterwikiMap

Problem
The list of default interwiki prefixes and URLs is based "more or less on the public interwiki map from MeatballWiki". Aside from the Wikimedia wikis, its approximately 93 items mostly include a rather random assortment of obscure sites, such as Seattle Wiki. The typical wiki owner finds himself needing to add prefixes to the interwiki table even for moderately popular wikis. The list should probably be revamped, if anyone can come up with some decent criteria for inclusion and a standard list of interwiki prefixes that everyone can agree upon.

Proposal
An extension, Extension:InterwikiPrefixes, should be created that periodically polls Interwiki list to get the latest interwiki prefix list, much as Extension:SpamBlacklist polls Spam blacklist for the latest spam blacklist. Extension:Interwiki should be made read-only, and there should be a MediaWiki:Interwiki-addlist and MediaWiki:Interwiki-subtractlist to allow site owners to customize their interwiki lists by adding or subtracting items from meta's list.

Probably FlaggedRevs should be used to prevent vandalism. It would be going too far to only allow sysop edits, unless the process for making requests and getting them granted were mostly a formality.

Collisions
Sometimes an interwiki prefix will be added that collides with a page title. For example, suppose you have a page on your wiki titled Commandos: Behind Enemy Lines. If someone creates a wiki called "Commandos" with the  interwiki prefix, then the page will become inaccessible until you run the appropriate maintenance script to change the title. This could get rather inconvenient.

To obviate this problem, there should also be a Special:InterwikiCollisions page that allows users to view which interwiki prefixes the extension wants to add to the interwiki table but can't because there is a conflicting page title. There should be ArticleDeleteComplete and TitleMoveComplete hook functions that detect when the last conflicting page has been taken care of, so that the interwiki prefix can be automatically added. (Conflicting page titles in the archive table,logging table, and anywhere else they appear, should be "legalized" at that time.)

Let competing lists be created
There should be a configuration setting,, that lets the site owner select a URL from which to obtain the interwiki list. Possibly, meta could simply link to a list of lists, and site owners could choose the one they want. Some lists might have different criteria for inclusion and dispute resolution. If this approach is taken, then the rest of these criteria questions below might be irrelevant to us, since they will be decided on non-Wikimedia sites.

Inclusion
Basically, any public wiki should be eligible for inclusion. There generally shouldn't be the kind of censorship against offensive or politically incorrect sites that occurs with the spam blacklist. However, illegal sites (e.g. warez trading sites) must be banned from the list.

The question of what non-wiki sites should go on the list is an interesting one. Obviously there is a huge number of such sites, and the potential for collisions (e.g. .com vs. .org) would be multiplied. But including those sites would also increase the usefulness of the interwiki list. Perhaps an inclusion criterion, such as being in the top 10,000 websites, could be set.

Resolving disputes
What if two wikis want the same interwiki prefix? Possible criteria for deciding who wins:
 * First come, first served
 * Names of the wikis
 * URLs of the wikis
 * Popularity, activity, size, importance, etc. of the wikis
 * Age of the wikis
 * How widely (if at all) the interwiki prefix is already used to refer to one of the wikis
 * Auction
 * Rock-paper-scissors-lizard-Spock