While cooking up our latest index-widget value meal, no one was surprised to find Batman mopping the floor with his crime-fighting allies. In not even four full weeks, summer blockbuster The Dark Knight has grossed $440 million domestically, and looks destined to give Titanic a run for highest-earner ever. Over the past 30 days, that’s led to 140,000-plus eBay sells for Gotham’s finest — incredibly, more than Superman and Spider-man combined.

With Terapeak’s new superheroes index, you can compare the total listings, total sales, and average selling price of eBay’s top-10-selling superheroes, from Iron Man to Spawn to Captain America. Running near-last in all categories is Green Lantern, but with a Warner Bros. film in the can for 2010, he’s one to keep an eye on. Finally, we apologize to fans of X-Men’s Wolverine, who was sadly omitted; he’s a top-seller, trust us, but the data’s just too skewed by the maize and blue of Michigan supporters, those weasels. (We mean that technically, weasels… wolverines… Mustelidae family…)

Click here to view the full index, and click here for a widget that embeds easily into any blog (also found on the main index page).