I keep a file on my computer full of random thoughts, snippets of imagined dialogue, and one-line descriptions. Sometimes one of these fragments runs to a full paragraph, but usually no more than that. Every once in a while, when I'm not feeling particularly inspired, I go there and skim through the fragments, seeing if something "takes" with me, and I start writing more.
I love a good writing prompt. One of the reasons I never feel at a loss for something to write about is that I like tossing in the occasional random element and seeing what happens. (It's also why I love getting a call for submissions on a topic that seems like it should have no interest to me whatsoever—I don't always answer them or have time, but then one will come along that makes me think, Well, why not? And I surprise myself.
I've been taking part in an occasional, informal writing workshop at the college where I live. It's touched on elements of pattern and rhythm, point of view, and so on. And there've been one or two free-writing prompts included in each session. One of them's turned into a short story that I'm writing for a workshop next semester.
Another thing that's been really helpful is a weekly email that comes out from Poets & Writers (if you don't subscribe, it's a great magazine; I highly recommend it). Called The Time Is Now, it includes prompts for fiction, nonfiction, and poetry. I copy each of the fiction prompts and save them in a file I can access anywhere (Evernote is a great tool for this). At this point, I have such a backlog of ideas I don't worry about ever running out.
What tools have you found for inspiration that you consider useful?