Microsoft Dynamics as an ERP Platform lends itself to being the ideal platform to which there are a plethora of customisations, plug-ins, extensions, and themes based on verticals, or job roles or legislations which exist to supplement and enhance the functionality of Microsoft Dynamics.
DynamicsWorld Microsoft Dynamics Top 50 Add-Ons 2013
Advanced Contract Billing Suite
deFacto Performance Management
http://www.dynamicsworld.co.uk/microsoft-dynamics-top-50-add-ons-for-2013 this will explain the list and show how the list was put together.