You should seek as much risk as you comfortably can over the course of your career. This simple heuristic helps you maximize career-long impact, both in your work and in your bank account. This risk profile self-assessment tool will help you understand how much risk you can comfortably seek.
I’ve profiled some dev shops (as well as agencies and other types of consultants) based on their web presence. Most are specialized in some way, and I hope these examples help you better understand how to market your specialized services. A few of these are clients of mine; most are not.
A comprehensive guide to specializing an indie consulting business
This detailed guide — aside from my book — is the most comprehensive description of how specialization works for indie consultants, how to specialize, and what to be prepared for along the way. It's free (no opt-in required) and useful.