Here's my survival kit, tailor made to get you out of many situations a cosmopolitan urbanite like yourself might encounter. I'll go through each item briefly, and give an example 'survival' scenario where it would be useful.
Step 1: Case
I used this stainless steel business card holder that I bought at the dollar store. I like it because it is sturdy and compact, and has no protruding corners that might get uncomfortable in a pocket. An altoids can or similar would also be a perfect choice.