Low Cost Webcast Optimizations?

ChunKing asks: "I work for a small community broadcasting organization, and we operate a limited streaming media facility for a number of not-for-profit webcasters. It has always been an issue to optimize our streaming media infrastructure to most benefit our users. We operate a small cluster of servers from a data center with good connectivity and a highly-rated ISP, who will occasionally allow us to burst to unlimited bandwidth. For big webcasts, we will load balance the stream over a number of servers using round robin DNS. However, we still get problems with stream buffering and network drop-outs, particularly with streaming video. We cannot afford a network of edge delivery servers like Akamai, so in what ways can we further optimize our streaming media capacity to better produce smooth webcasts?"