As I prepare to ship v1.1 of Six to Eight, I'm curious as to what ideas other people might have for Stack Exchange app marketing. How do we reach Stack Exchange users without either annoying them with spammy messages or spending a fortune (or, indeed, anything beyond time).
Six to Eight has been about as successful as I'd hoped so far. I've shipped around 1000 copies: around 450 on the day it first hit the App Store and Jeff tweeted it, 150 when it came 3rd in the SE API competition, then a steady trickle at about 50 new downloads a week. I'm happy, but I think there're more users out there who might like it.
My only real ideas so far are posting on the meta sites, which I've rejected as being too spam like. I guess I could buy Stack Exchange ad space, but I've got no marketing budget for a free app. I like to encourage users to spread the word, especially to the audience on the new Stack Exchanges, but I don't know how.
How are other developers promoting their work, and what can I do to encourage more adoption?