Downloadable content is supplemental material that video players access for a small fee to add new features to big-name retail games like Activision Blizzard’s (NASDAQ:ATVI) Call of Duty: Black Ops. And Activision’s recent quarter demonstrated how valuable such add-ons are becoming to the bottom line.

According to Activision CEO Bobby Kotick, digital content accounted for about 30% of total revenue for the period, totaling $428 million compared to $330 million in 2010. This revenue came from big downloadable releases like the Call of Duty: Black Ops add-on “First Strike,” which was released in February, and the continued sales of December’s Cataclysm expansion to the online role-playing game World of Warcraft.

For investors following the industry, here are three other video game stocks that figure to replicate Activision’s success with downloadable content.

Take-Two Interactive (NASDAQ:TTWO)

Take-Two, like Activision, is increasingly relying on supplemental material to maximize the profitability of its big retail releases. Red Dead Redemption, made by Grand Theft Auto creators Rockstar Games, sold 8 million copies between May 2010 and February 2011, a milestone reached thanks to sales of add-on content like Red Dead Redemption: Undead Nightmare. Take-Two will release he latest game to bear the Rockstar brand, hardboiled cop drama L.A. Noire, on May 17 and it is already supplemented with downloadable content procured by pre-ordering the game through Wal-Mart (NYSE:WMT).  The company will undoubtedly release additional content for the game throughout the year into the holiday season, guaranteeing a steady stream of revenue.

Microsoft (NASDAQ:MSFT)

Microsoft was one of the first console makers to capitalize on downloadable content, due in no small part to the combination of its popular online gaming service Xbox Live and the Halo game franchise. Even though Halo-creators Bungie are now working with Activision, downloadable content for the Halo series continues to earn for Microsoft in 2011—the first downloadable package for Halo: Reach that wasn’t made by Bungie, the “Defiant Map Pack,” was released in March, and has remained one of the most downloaded pieces of content on the Xbox 360. Microsoft is expected to release a remake of the original Halo in November,  which is guaranteed to see a lot of extra digital content before the end of the year.

Time Warner (NYSE:TWX)

Time Warner’s video game business is performing admirably this year, as demonstrated by its first quarter earnings report. The company’s big April release, Mortal Kombat, sold 732,000 in its first week of sales and the company is already planning to release paid downloadable content for the game this summer. The company’s main release for the fall, Batman: Arkham City, is expected to be a multi-million seller during the holiday season. That game’s predecessor, 2009’s Batman: Arkham Asylum, saw a number of downloadable content releases, so it’s safe to assume the new title will be supported as well.

As of this writing, Anthony John Agnello did not own a position in any of the stocks named here. Follow him on Twitter at @ajohnagnello and become a fan of InvestorPlace on Facebook.