Eventbrite announced Wednesday the closing of a $20 million Series D round of funding led by DAG Ventures with participation from new contributer Tenaya Capital and Sequoia Capital, previously the company’s sole investor.

Easily Eventbrite’s biggest round in its four years of existence, the Series D brings the company’s total funds raised to $29.5 million.

Having already processed 7.5 million tickets in 2010, Eventbrite, undoubtedly one of the Web’s most popular event registration sites, says it is on track to see $200 million in gross ticket sales this year. While half of those 7.5 million tickets are free, the average ticket price is still $60. Eventbrite takes a small cut from any ticket sales.

In spite of Eventbrite’s recent milestones, the San Francisco-based company realizes it still has a great deal of room to grow. Hence, the need for a fundraiser.

“Today, there is only one destination site, Ticketmaster, to find events that are going on,” said founder and CEO Kevin Hartz. “We think that needs to change.”

Hartz’s company could easily attract new sellers from Ticketmaster because only the latter company somehow finds it fair to charge exorbitant service fees. Additionally, Eventbrite has the advantage of harnessing social discovery tools, via the Facebook Connect APIs, that enable users to share events with each other. Facebook now drives more traffic to the site than Google.

To reach more users, Hartz also wants to market his company more outside the United States. Since only 15% of its gross ticket sales come from outside the U.S., Eventbrite will begin aggressively pushing its service internationally. The Germany-based Amiando is already a major force in Europe for event registration and ticketing.

International and financial expansion, therefore, are the issues most pressing to Hartz. He has responded to the option of an IPO in the same manner as CEO Mark Zuckerberg of Facebook and CEO Mark Pincus of Zynga; all three companies have exhibited massive early successes and have even collected significant revenue, but none is quite mature enough for the public option.