One of the many neat little things about Scrivener is its ability to set “target” word counts. Personally I waffle about what amount to shoot for all the time—my current feeling is that 500 is a good minimum because it’s fairly easily achievable (even easily surpassable).
But, I’m frequently not writing in Scrivener. Blog posts like this one tend to be written in Byword, and lately I’ve been using Ulysses 3 for shorter fiction. (Scrivener’s ability to serve as a collection bin for all kinds of research bits still gives it an edge over U3 for, well, long stuff that needs research bits.)
I realized not too long ago that I could hack together a “daily word count” system with Keyboard Maestro. It’s not as elegant as Scrivener’s; it doesn’t reset automatically, and it doesn’t give you neat progress bars. But it gets the job as I need it done.