I dual-boxed in BC for a while before moving on to 3-boxing, then 5-boxing. Depending on what you want to do, dual-boxing can be a lot of fun.

I didn't do very much with broadcasting, the only ones I used were follow and nuke. I used a feral druid and mage, and it was fun doing instances together. It was a lot easier to micro-manage as well. You're not going to be able to run instances by yourself, obviously, but it's still a lot of fun :).