A thousand words:
http://www.tomatoville.com/showthread.php?t=16486
I add lots of compost and composted manure to squash beds and Plant Tone around the plants. I don't think they are too particular if you prefer miracle gro, osmocote, or granular.
For the original question, My first thought was also problems with pollination, but now I recall sometimes having a particular plant that would do this. After 2 or 3 funky fruits in a row, I would yank the plant because I had others that produced perfectly good fruits.