How can I auto tweet any node of a specific type to Twitter?
I ended up doing this with Rules, Rules Bonus Pack, Views, Flag &amp; Twitter Modules.

Set up a Rule that is:


Triggered during Cron runs.
Has no conditions
Loads a list of Node IDs from Views (Rules Bonus Pack)
Posts to twitter based on the first NID in the view. 


For my view, I made a flag called Tweet This attached to my node type, and the view displays nodes that have this flag.  You could use a different method to grab the list of nodes you want to tweet, such as filtering by date posted (get older content based on a given date) or number of views (popularity).

Good luck!