BinnyVA basically aggregates all my feeds and shows them in a calendar. The idea is to use this calendar as a Seinfeld Calendar. Don't know what a Seinfeld Calendar is? Here is an except...
... get a big wall calendar that has a whole year on one page and hang it on a prominent wall. The next step was to get a big red magic marker.
... for each day that I do my task of writing, I get to put a big red X over that day. "After a few days you'll have a chain. Just keep at it and the chain will grow longer every day. You'll like seeing that chain, especially when you get a few weeks under your belt. Your only job next is to not break the chain."
The difference is that my calendar is virtual and public.
All I have to do is 'Don't break the chain'. Make sure that each day has at least one post in it. Its going well for the last 2 months.
A word of warning before you use this method for your sites. Although the quantity of post goes up, the quality may come down. If you have not created a post by 11 at night, you will be forced to write something - and that something is often below par. It happened to me more than once.
It goes without saying that my calendar has another benefit - Google Juice. Each and every post on all my sites have at least one link from an external site. That can't be bad.
On a related note, there is a combined feed of all my feeds - powered by Yahoo Pipes.