Almost each Symfony project uses FOSUserBundle because it speeds up the development and provides useful features to manage users. It has a few built in storage layer implementations: one for Propel and a few for Doctrine (both ORM and ODM). It's great, but there are some cases when you have to use another storage. Luckily, FOSUserBundle is flexible enough and provides a way to implement a custom storage layer. You just need to implement your own user manager to use all features of FOSUserBundle.
It's a common need to integrate a payment gateway into a project. Even though there are many well known systems and aggregators like PayPal, RBKMoney, Paymentwall, Robokassa and so on, I want to talk about Paysera. It's another quite new payment system. They claim to have low commission fees for a convenient and wide range of services. Paysera allows your users to pay via cards and SMS. Integration is quite easy, but has some unclear moments during the process that I want to point out.
It seems obvious that almost every application has its configuration. We can use a lot of data formats for configuration files, for example YAML or XML, JSON or plain PHP (replace with any language you use) files. Personally I like and prefer to use YAML to other formats and here I just want to describe a little one of Symfony components called YAML. Also It's quite interesting for me which format you use, what pros and cons you see, so don't hesitate to leave a comment with your thoughts.