I've never been totally successful in waiting till the exact opportune moment to till my garden and I don't suppose that I ever will be.
I usually till my garden once or twice and when I'm ready to plant I am greeted with tremendous dirt clods (more than my 2 year old son has the tenacity to smash with a hammer). I could till it again, but generally part of the garden is OK, so I plant a few rows and then find that I've got really bad conditions in the rest of the garden. So I get out the mantis and do what I can.
What can I do after I've screwed up everything besides find a new part of my lawn to decimate? What I'd like would be some sort of soil amendment that can magically unclod my dirt as easily as I could do with a pitchfork or hammer after a good rain.