What are some good cash crops for a farmers market?

I always look for something fruity when I'm at a farmers market.
I'm rather partial to a prickly pear or two, but am willing to try anything on offer as long as it's fresh, of meaty texture, and is rather well hung.

Early tomatoes , if you grow them in a hoophouse and sell before most everybody else you can make good money.  Green peppers too they are a buck a piece sometimes in the off season.  You can make a mini hoophouse fairly cheap. Lots of plans are out there.   If you are selling in a college town with students from other cultures, baby corn and snow peas are ok but it depends on the demographics.  Unless you have them early, cucumbers and zuchinni can hardly be given away when everybody else  has them.  
Another product you might consider is potted plants, tomatoes, peppers, flowers, for people that want to start their own garden.

For the later season pumpkins (do not plant too early or they rot before halloween) and butternut squash and other winter squash (has the advantage of little perishability problems).

Good luck!

Anything you can manage to grow organically.  You can really charge a premium for that.  

My nephew made pretty good money with a half acre.  I don't remember everything he grew, but I'm sure there were sweet and hot peppers, and new potatoes.