When you write all the time, it's easy to feel like every concept in the universe has already been exhausted. I understand your pain. If you think your idea pump could use a good priming, you might want to start thinking outside the box. Here are a few unexpected sources of writing inspiration.
PostSecret is one of my favorite places to get story ideas. This website "is an ongoing community art project where people mail in their secrets anonymously on one side of a homemade postcard" (PostSecret). The secrets range from trivial to life-changing in significance and are accompanied by pictures that may or may not relate to the confession. When I want inspiration, I look here first. Sometimes you can get plot situations from here, but more often than not, you'll come away with at least some interesting character quirks.
You can also find ideas from magazine article titles. This method works better for creative nonfiction, but if you get creative, you can still apply it to your short stories and novels. I wrote a piece not too long ago titled "Five Ways to Make Him Stay" about a troubled marriage. The title came straight from Cosmopolitan. You can also get ideas from news headlines, which tends to be my preference.
Another excellent source for writing inspiration is the re-imagination of actual events--whether from your life or from someone else's. This method can also be very therapeutic.Take an encounter and turn it on its head. How could the event have happened differently? What could have been some of the consequences?
If you're still having troubles finding idea, consider this model to set up a story:
A _____ wants _____, but ____ gets in the way.
This model is the one I use for most of my stories. My most recent short story, "Teacup," looks something like this:
A creative writing professor wants to have a romantic relationship with a pretty girl, but the fact that she's a student gets in the way.
This format is very basic, but it can be surprisingly helpful. The same is true of the preceding methods. The next time your mental well is running dry, poke around one of these unconventional sources of inspiration.