WPCandy releases a Sample Posts Collection file, i.e.: dummy contents you could use to populate your newly created WordPress installation, good for when you’re developing new themes or plugins. There’s also another collection made by Stu Greenham.
I’ve been using the dummy content from the Sandbox competition happily all this time. So check that out, too.
[...] planning to release a lot of themes, it might be a good idea to create your own test site, add a dummy content into it, and upload your themes [...]