Open source is a great idea. I have been implementing a of of open source solutions, in PHP, .NET and Java. No Ruby project yet. For SMEs (small and medium enterprises), they definitely could not offer the price of SAP, or SIEBEL. However, they do not mind paying for a small sum of money to help them implement open source solutions to help running their daily business operations, and also support the software. Here I am going to show you some of the great business solutions that could definitely help small to medium businesses. The list is not mean to cover the “top” or most “popular” software out there. There are definitely a lot of open source solutions available for the same domain space. The list here is just based on my project implementation experience. If you have a second opinion, do let me know.