Linda Formichelli has a great blog on finding article subjects called 8 Tips for Generating Salable Article Ideas. I love her site, The Renegade Writer. If you're writing freelance, you should check it out.
I'll add a tip of my own for essay and article writers. Try using smells to generate memories and associations. Smell is a strong brain trigger for memories, so use it to brainstorm about what the smell reminds you of. (Yes, you can end a sentence with a preposition now.) I use this with my class sometimes to help them think of possible essay topics.
Maybe smelling baking bread reminds you of your flour-covered fingers kneading dough in your grandmother's kitchen. Then you can write an essay about your baking memory and submit it to Chicken Soup for the Soul. They are looking for stories about Baking With Kids. Share your loaf lessons of childhood baking and you may get published. And don't forget to incorporate sensory information into your writing. It gives it a whole new dimension and texture.
Some other smells to scratch and sniff for ideas:
roses (yeah, corny. I just told you to stop and smell them)
Today is the morning Coffee and Critique Meeting. Hope to see you there.