Are there any mods out there that track the modification of posts? IE someone edits a post, and I log in and (with full post-tracking) and see in red "(1 edited)", or something like that?

The closest to this that I know of is the admin log.

Nope there are no modifications here for that. If you really need something like that you can post in the Developers for Hire forum and see if someone will write this up for a small fee.

Oh, I could do it myself if the demand is high enough - I was just wondering if something like this existed already in any form, before I make it.

Hehe I gave it a quick try -- looks like this is something that just isn't easily doable. If it gets tied to post tracking, it'll only either indicate posts edited that the user hadn't already read yet, or if you remove it from post tracking the edit tag would never go away.

Probably the best method of doing this (if you wanted moderators to easily be able to track post edits) is to create a moderator script that lists all the recently edited posts.