Did a couple searches for them in January and still haven't gotten paid.  Avoid them!! We try calling them but always get a voicemail. 
They have a web page:
http://www.cornerstoneltd.net/

Has contact info for a sdeegan@cornerstoneltd.net

Apparently a Sean Deegan.

Nothing comes up with a google on the number they show of 631-421-9535, but a google of their fax number 631-425-0863 brings up this web page:
http://www.cornerstonerecruiters.com/index.html

Which shows a phone number of 631-425-0312.

Here is what I found with a domain search:
http://www.checkdomain.com/cgi-bin/checkdomain.pl?domain=cornerstonerecruiters.com

Anybody have any ideas on how to leverage our money from these folks?