Interns are college students. College students can be kind of dumb about job searching... for the most part, they will tend to apply to the companies who come on campus, and ignore the companies that don't. Pick one or two campuses and go all out to recruit there and you'll find some. There are some colleges that have a particularly high concentration of good CS students: UIUC, Stanford, Rose Hulman, Waterloo, and MIT are all good bets.

For a whole BOOK about recruiting on campus:

http://www.amazon.com/Recruit-Die-Business-Young-Talent/dp/1...