When I'm talking about a 'development board', I'm meaning a common board which can be used for most applications. I didn't planned to sale this product, but it will be part of own experimental projects and also profesionnal projects.

Erik, I can understand that designing a board like this is already done by companies with an attractive cost. However, from my side, I prefer to design a board myself because, the cost is lower for prototypes and I can design precisely what I want (for connections, peripherals, size, technology, component choice, and so on...)
Some applications have constraints like extended working temperature (military) or specific power supply. I will implement a switched regulator to be compliant with power in voltage up to 35V (for 24V embeded automotive application and European's standards)
That's why I've chosen to design instead of to buy. However, I agree to say that I could probably find an existing board filling all my requirements, ... but I also enjoy to design.

I'll take a look for the Tricend E5. I don't know this product at all but for the moment, my feeling is for the 89c668 if I can find this chip here in France

Stephane