The Symfony project has posted a Top 20 list of the most accessed plugins for the framework, as based on their stats:
A quick look at the analytics of the symfony website tells us a lot about what people need in addition to the symfony core. Here is the top 20 plugins based on the number of page views of the corresponding wiki pages in the last 30 days.
Among those on the list are things like:
Check out the full list for other great plugins that made it into the Top 20.