While doing some research for some work on an emitter for a client, I came across the Arctorus BIRT Emitters. I'd never heard of these guys, just the standard OSS BIRT Emitters, the Commercial BIRT Emitters, and the Tribix Emitters. While these are commercial emitters, and are not free, they do offer a 30 day trial. These are the formats that are supported.
I intend to do a review of them and see how well they work.