I've been involved in the organisation of a number of scientific conferences over the past few years. For example 4m/ICOMM 2009 (submissions), I*PROMS 2009 (submissions). The conference sites are usually powered by drupal, the submissions using OpenConf. Managing the submission and peer review of papers is a chore, unfortunately, as is often the case, software gets in your way. So here I try to skim over some of the experiences I had with OpenConf - the good and the bad.
I've tested indico, which looks like a very good system, but it is heavy and over-engineered, especially if you want to run a couple of events, and not hundreds or thousands. It might be good for organisations managing a big number of events, but not for us.
After going through a number of trials I've settled on openconf. It was simple. It fitted the current web infrastructure - LAMP. I reckoned, I could eventually integrate it, or simply transfer some of the data into drupal, and maybe even benefit from code reuse. Surprisingly, I ended being both pleasantly surprised and not so.