Links or diffs submitted can be placed in an AutomaticSandbox until PeerReviewed if losing information is a concern, although this opens the SandBox up to being a spam pit. You could simply break the links in the SandBox (e.g. display as h t t p://usemod.com) or put them through an ExternalRedirect?er or make them NoFollow, although NoFollow is unlikely to dissuade spammers.
Additionally, if you're particularly aggressive, you could put throttled links directly into a BannedContent? list, say in preparation for the PeerToPeerBanList. You could even automatically GlobalRevert all edits by any editor that has crashed through the throttle (a la CitizenArrest). Doing this is inadvisable as a false positive could be disastrous.
Unlike EditThrottling, LinkThrottling is unlikely to interfere with normal editing as most editors do not blast a large number of external URLs. An exception would be when a commonly linked to site (e.g. SlashDot, FlameWarriors) changes its URL structure or domain name. In that case, the throttle will be a huge problem, particularly if you automatically ban and CitizenArrest throttled people.