There isn't a specific checklist programmers check before saying, "Yep! I think I can work now." Most of us gauge our knowledge by helping out on forums/boards/in person meetings. If you can help people with programming problems, you consolidate what you know and you demonstrate your knowledge.
Look around job boards online and see what the common requirements are for your given language. Python, for instance.
What is generally asked for a python job listing?
Google App Engine knowledge? Pygame? TKinter?
Find that out and you will see how 'marketable' you are for a job.
Having said that you are a programmer - many programmers don't even know what an interpreter is, let alone create one.