Yesterday we wrote about a new cross-promotion bar for Facebook games called Appstrip. It’s the second of a new type of promotional tool, built by and for small Facebook developers. The first? Applifier, which initially described itself to us three months ago as the “Rebel Alliance” of Facebook.

Applifier isn’t rebelling against Facebook itself, of course (that would be like Luke Skywalker going up against the physical universe). Instead, it’s pitting itself against the Death Star — Zynga, with its 200+ million monthly active users. Not to mention the Star Destroyers represented by Playfish, Playdom and CrowdStar, which have between 35 and 55 million players each.

Besides the obvious advantage of more money, those networks create a big edge over smaller opponents. But Applifier is at the very least larger than Playdom, according to CEO Jussi Laakkonen, giving small developers access to somewhere over 35 million users across the network.

Here’s how it works: above or below each of its Facebook games, a company like Zynga will advertise its other games in a promotion bar. Player traffic between these promoted games are a significant source of growth and player retention.

Lots of smaller developers only have a handful of games, or even just one. Applifier creates an artificial network by providing a strip promoting games from other developers, while elsewhere on the network the original game is being promoted. For the most part player traffic is just traded between games, though Applifier also takes a small percentage of traffic and sells it back into the network to developers that want to grow faster.

When it started, Applifier could only be accessed by developers who had been introduced by someone else. However, Laakkonen says that it’s now open for anyone to apply through the website. He’s also opening to non-game entertainment apps that provide value to users (in other words, not spammy quiz or poke apps).

“What’s interesting is that nobody has left, over the three months that we’ve been going. If Applifier didn’t work, people would leave,” says Laakkonen. “Applifier doesn’t exist without its members. It’s a service that will only work as long as we have the trust of our members, and they’ve seen how well we perform.”

Although we’d set up a time to speak with Laakkonen before Appstrip emerged, the new competitor, which is run by game developer and Applifier member Broken Bulb Studios, naturally came up. Laakkonen claims to be happy that there will be competition. At the same time, he seems somewhat annoyed with the form it has taken. “I do think it’s a clone,” he tells us.

For his part, Broken Bulb CEO Robert Nelson told us Wednesday that he created Appstrip as an alternative to Applifier because of technical problems in the latter. The two have yet to work out their differences, so there’s the potential that Broken Bulb will end up getting pushed off Applifier.

Other developers should benefit, though, since they’re free to use both promotion strips if they choose. Laakkonen says his company’s goal is just to improve life for small developers. “I come from the console games business,” he says. “In that space you have huge gatekeepers, like Walmart, publishers, and as a developer you’re so distant from your customers you wouldn’t believe it. Here, with all the changes that have happened on Facebook, it’s still an amazingly friendly ecosystem, and an amazing opportunity for an independent developer.”

In the near future, Applifier will be releasing some unique tools that leverage its large network, according to Laakkonen; we’ll write about those when more details are available.