Just for going out or staying local, I can see the point of something small and neat, wiht one or two cards. I often take a money clip with me and leave my wallet in the the safe. Otherwise I have:

Biz Amex
My Amex
My Credit Card (Miles)
My Debit/ATM Card
My FX Credit Cards (No miles, No Loading)
FFP Cards x 3
Priority Pass Card
Driving Licence
ID Card
Oyster Card
Starbucks Card
Costa Card
SPG Card (Has all the other numbers on it!)
Biz Cards

UK + € + Wherever I am currency

Lots of Receipts