One of the best sources is going to be scholarships available from the college itself. Other than that, there are scholarships available from countless sources.
Local Community Foundations often have a scholarship fund (I.e. the Community Foundation of Western MA serving my county and a few others here in Western Massachusetts).
There are also lots of helpful scholarschip websites, my personal favorite is www.fastweb.com in addition to these, checking out any type of local service clubs, unions, and places of worship is important, especially if the student or his/her parents are involved in that organization. I know that local Rotary Clubs and Lions Clubs often have scholarships each year, as do Italian-American, Polish-American etc. etc. and similar clubs.
Hope this helps! I actually have a hub on it as well, all about finding scholarships online.