Digital media holding IAC today announced its acquisition of DateHookup.com, which it bills as “one of the largest ad-supported online dating sites in the United States” with more than 1 million unique visitors per month.

Financial terms of the acquisition were not disclosed, sadly.

DateHookup will become part of IAC’s portfolio of online dating businesses, which the company claims generated more than $500 million in revenue in 2011.

Other IAC businesses in that category include Match.com, Chemistry.com, OKCupid and OurTime.com, among others.

DateHookup was founded by CEO Dustin Weirich in 2002 and has grown to become the 6th most-trafficked free online dating website in the US.

The site monetizes through online ads and charges on a CPM basis. The minimum purchase for ads is $5,000 per month, and DateHookup offers only US traffic.

Buyer IAC, started and run by longtime media exec Barry Diller, is listed on NASDAQ and currently boasts a market cap of over $4.5 billion.

The company recently made headlines when it acquired About.com from The New York Times for about $300 million in cash.