Ask HN: What are some enterprise markets hackable by individuals?

Patrick Mckenzie @ Kalzumeus blog tells the story of how he was able to sell his scheduling app to big hospital. I'm wondering what are some opportunities in the enterprise space that an individual can tackle? Can I simply build an ERP, get some complicated looking ERP website and have user's contact me for a one on one sales call or a meeting? I'm just trying to see how I can hack my way into an enterprise customer's hearts.