A two part series over on the Resurgence blog on what is meant by 'calling'. Let's start with some quotes:

...we have so many people sitting around waiting on a warm, fuzzy, and goose-bump-inducing vision from God before they embark on some ministry. Maybe we've invented the whole language of calling to mask the fact that most Christians don't want to live missionally.

So let me say it plainly: I don't think you need to be "called" to go overseas, any more than I think you need to be "called" to live missionally wherever you are. As a disciple, you must ask, "How can my talents best be used in God's worldwide mission?" If the answer is that you can be part of an overseas community-building, Jesus-preaching project, don't wait for a special calling. Pack your bags.

Primarily they are talking about overseas mission in this article, but the vibe of the article I think in some ways reflects how I understand my calling to ministry. My talents, gifts and abilities are best used in worldwide mission by being involved in paid local church ministry, and due to a lack of practitioners, it's strategic value, and the circumstances I have found myself in over the last 4 or 5 years, I have had my focus on Youth Ministry. This may change, but for now, this is where I'm at. I think of my call more like obedience to God and my gifts than as a response to God whispering in my ear. I actually think that this attitude helps me through the tough times somehow...