Q: Are you or might you take the application open source with the hopes of being the next Wordpress, Drupal, or SugarCRM?<p>A: PHP -- simply because it's so easy for people to install and run PHP apps. At this moment in time, I think almost all of the 'breakout' open source apps have becomes breakout hits in part because they're written in PHP.<p>You can do quite a bit in PHP. Facebook's FBML parsers are written in PHP and Flickr's home-brewed queue-based background processing system is written in PHP. Yes, PHP is difficult to stare at all day because of the $,->,=>,@, and ; (and soon /), but it's a perfectly fine language otherwise.<p>Python would be my choice if my web app required a lot of algorithmic work. If, for example, I was performing a lot of text analysis, I'd choose Python. They have a number of built-in operations and operators that make it easy and concise to do such things. I believe that the original Google spiders were written in Python. And there are numerous libraries for do statistics, advanced math, and such things in Python. If your web app can be built on-top-of Google's App Engine and doesn't require https (assuming you use your own domain name), then that might be a good place to start.