If you'd like to use any of these, to refine, colour or whatever, feel free. I'd very much appreciate it if you link back to me though, and send me a link to your image(s)... mostly so I can see what kind of cool stuff you made.

(DOWNLOAD for larger image.)
Some creature type silhouettes created primarily using various Pull Shapes in Alchemy.
Alchemy is a lot of fun to use, and it's free! It can be downloaded here:
[link]It's a shape-generating drawing program that acts as a great tool for generating silhouettes and outlines, using a more or less Rorschach-like method of your being able to pick things out (like facial features and humanoid forms, for example).
So for those times when you have a dry spell of "artist's block", you now no longer have an excuse!

Once you get the hang of it, it's reasonably easy to use, and really very fast -- most of these images were created in under 10 minutes. Some, quite literally, took only seconds. SECONDS!
(Not quite sure if this is in the right category. If you think there's a better one to put it in, please let me know which one.)
What I generally do is draw with the "thick" Style, alternating between black and white (they can be switched quickly with the x key), with each being at about 1/3 transparency, using the Pull Shapes mode in the Create dropdown menu, and the Mirror option in the Affect menu (that's probably sounds a lot more complicated than it actually is unless you have Alchemy open and are looking at it). Once I have something I'm starting to like, I crop out the parts I don't want with a fully opaque white, on the "thin" Style, using the Shapes setting in the create menu (and similarly add stuff by hand as I feel is needed).
Then I generally take a screenshot and bring it into Photoshop and add a speck of colour, but that part's really not too necessary.
So there you have it! Fairly random, high-detailed-looking drawing made quick and easy.
To get a taste of just how quick and easy it can be, there are a number of videos on YouTube that you can look at, including this one: [link]