Please feel free to complete the arabic translation I am sure there are people out there that would appreciate it.
Of course there are many benefits of contributing to an opensource project.
1. Living in the knowledge that you can do something for other people without wanting something back.
2. The feeling of being part of the community by investing time in the project
3. The thanks from people that use your contribution.
There are also many other benefits.. if there werent then no-one would ever contribute to an opensource project.
In terms of commercial services there are non at present that come from contributing... the only way to get a banner etc is to join the sponsorship program.
see http://www.oscommerce.com/partners/corporate,info