After last night, I have really found an appreciation for external flashes. I'm in college and last night our main street (Franklin Street) was crowded with something like 15-20,000+ people. Lightly put, it was crowded 
Anyway, I started off the evening taking pictures with the onboard flash of my 20D and sometimes bumping up the ISO and not using a flash. A friend of mine has an old Rebel that he has that has an external Vivitar flash that he got for like $20. I stuck it on my 20D and used it a bit, and saw a world of difference in the quality of my pictures up close with it (much more light, of course). However further back in the crowds (maybe 25+ feet away), it was somewhat darker.
I'm wondering, is there a flash that'd allow me to get more range with my light? I'm seriously wanting to get a flash now (maybe the 550 or 580?) and want something with good range.
Thanks!
