Specific documentation for 80legs is available at http://wiki.80legs.com. To get fancy, you may want to check out http://wiki.80legs.com/80apps to make your own custom extractors. Note that any custom extractors you write will output files in binary in 80legs, so you'll need to convert the byte array to .txt, .csv or .xml or whatever format you want.

(We post custom extractor results as binary because you can also return stuff like images!)