I was incredibly surprised to discover that there isn't a daily Farmer's Market/facility here in San Diego. I mean, the climate is perfect for it! Alas, we have to make do with various farmer's markets strewn about city parking lots that rotate locations throughout the week. The Hillcrest Farmer's Market is one of the largest ones.
It is located in the DMV lot and runs Sunday mornings through early afternoon. Parking usually isn't too big of a hassle, but it can be annoying. There are probably about fifty - sixty vendors selling everything from produce to jewelry to sauces. Favorites of mine are the guy that sells the cacti for $1, the candle stand (she'll even give you a free sample to try out a scent), and the stand with the organic lemons. I find most of the produce is rather overpriced (yes, I understand that it is organic, but I can get locally grown organic produce for sometimes 1/4 of the cost of what's at the market -- see my review of the Be Wise Ranch CSA) but very fresh. The clothing and jewelry stores are pretty standard -- you will recognize them as having the same styles as most street/crafts fairs everywhere.
The food stalls smell great, but after suffering from food poisoning from one of them, I have not gone back to sample any more. There is usually music in the center of the market, and it is fun to see everyone out with their straw baskets filled with fruits and veggies.