Here is an intersting link:
http://usaca.com/
These are the biggest ticket consolidators in the US. They do only wholesale, so they will probably not work with you directly. However, they can probably suggest a subagent they work with.
Another intersting thing is that despite what people think or say, most of these consolidators have the same fares. They all have the same contracts with the major carriers (DL, UA, AA, US, LH, CO, AF, JL, LX, KL). Some may have contracts with smaller airlines, and those are the ones worth of exploring.
The consolidation is another distribution channel for the airlines. For certain markets, it makes more sense to distribute through the consolidators because it is more efficient. This way the airlines focus on markets that are high yield and require "less work".