Just to contribute a bit:
I sent a goodwill letter to Capital One regarding a 90 day late in Jan 2008, explaining that I over-extended myself during the holiday season while visiting family. I also explained that I didn't realize the impact it would have on my credit score. I asked that they consider revising it since I've kept the account up since, since I bank with them, and since I'm weighing the possibility of moving two retirement accounts from former employers to an account with them.
I'll post my letter when I get a reply from them, and their response (yay or nay).
This forum has been great, and I hope to be able to contribute a fraction of what I've gotten out of it. I'm only a few months into seriously hawking my credit reports. Still learning a lot.