Life Admin: The Necessary Paperwork

Thanks to David for asking a question that I think prompts a post about my response-what paperwork/legal documents should you plan to bring to the UK when you move?  With the benefit of hindsight, I can only say this:  Bring everything you think you would need-and even everything you don't think you will need.  In other words, if it's an important document to you in the US, it will be equally valuable to you in the UK. If not moreso.
My list of documents-in no particular order- I've needed/reference on a regular basis include:

1. My passport-kinda goes without saying
2. US Drivers license-seems to be acceptable here as a form of ID (I've used it at the Post Office to collect packages..)
3. College transcripts
4. College diplomas-an odd one, but I did have to have this for my Tier 1 visa app
5. At least 3 years previous tax returns.  A. You'll want a few to help your tax pro when preparing your current year TR-and B. You could end up being the fortunate recipient of an IRS Audit letter of a recent tax return filing, and you'll want to have a copy of your returns handy.
6. Birth certificate
7. Social Security Card
8. Marriage certificate-certified
9. US Home mortgage paperwork-deed & loan docs
10. Immunization/Medical Records-probably even more important if you have kids

It will only take up a bit of space to have these handy-but could save some serious stress (and cost) if you suddenly have a need for one of these-and have to put an express order in.  Yikes.  

At some point in my 4 years in London, I've needed every one of these docs.  But, I'm probably missing a few things that I'm just not aware of.  What else? What other documents have some of you had to have?