libcraigscrape is an easy library to do the heavy lifting between you and Craigslist's posting database. Given a URL, libcraigscrape will follow links, scrape fields, and deduce Ruby objects out of the raw HTML from Craigslist's servers. libcraigscrape was primarily developed to support the included craigwatch script.
As part of the FRDCSA Job-Search system, Job Search Rapid Response is a GUI tool to allow one to respond very quickly to job offers on Craigslist, as this seems to be important. It allows one to fill out a standard template to send, but will not allow it to be sent unless a certain amount of changes have been made to the template. It makes a PDF of your cover letter and attaches your resume. It allows for VoIP calling (currently using Twinkle) of phone numbers in the postings based on 1 click, and Googles company names to aid in research. It keeps a database of all communication and can track responses in an IMAP folder. Eventually, full integration with job searching is planned.
jobSeeker is a class that searches for jobs on a range of different job sites. It takes a list of parameters for searching for jobs, such as keywords, country, city, distance limit, and the sites to search. It returns an array of results that includes the job title, description, and job page URL. Currently it supports Craigslist, Indeed, and Monster.