Originally from South America the peppers were brought to the Padrón region of Spain in the 16th century.  These small green peppers have since gained world-wide popularity.  While the shape varies from pepper to pepper (and so does the heat) they are typically a little crinkled, about 1 to 1 1/2" long and look like an elongated habanero.  These are (mostly) sweet peppers but for some genetic reason about every 10th pepper on a vine is hot.  The peppers are usually sold green but if they allowed to mature on the vine they will turn red.

The peppers may be brined, or fried whole in olive oil and lightly salted (a Spanish Tapas bar favorite).  When picked red the padron can be dried and ground into a powder similar to paprika.

Padron peppers have become a favorite in many farmer's markets and some well-stocked grocery stores.  They can also be purchased online.  See where to buy.  You can buy seeds at Localharvest.org