5 Tips for Finding Seasonal Temporary Employment.
Well worth reading - good ideas to shape your part-time job search.

Boston College Student Employment
Part-time jobs - on-campus and off-campus listings.

CollegeHelpers.com
NOTE: this is the same system where BC has off-campus, non-Federal Work Study employers list their jobs.

Craig's List - Boston-area part-time jobs

GotaJob.com
Lots of summer and part-time jobs, all of them paid jobs.

SnagAJob.com
Completely free job-search engine.  It is the nation's number one source for part-time and hourly jobs with over 100,000 active jobs postings.  Great for students who are looking for summer jobs, part-time gigs to help them earn cash during the school year, or a post-graduate job in the hourly field.

Urbaninterns.com
New website aimed at connecting small business owners and professionals with those seeking part-time flexible work.  Internships are both paid and non-paid.