Security clearance placement agencies?

[scott at ehrlichtronics.com (Scott Ehrlich)]

I once had a security clearance, and would like to regain it (it has been
longer than two years, so mine is no longer considered active).

I know LockHeed Martin is a contractor that services many
organizations with positions requiring either an existing clearance or for
a potential candidate to be able to obtain a clearance if hired.

Along the lines of Lockheed Martin, what other
companies/contractors/headhunters either cater to or have a sizeable
listing of security-clearance types of jobs for the Eastern Mass area?

Since I no longer have an active clearance, someone catering to
active-only clearances would not do me any good.

I'd rather work with a company/agency which caters to this area rather
than apply on my own to an available position.

Thanks in advance.

Scott