"Finally, yes there are load of projects that already do REST / HTTP APIs but sometimes it's very useful to look at the underlying technology from scratch. Not great for production use but brilliant for learning a technology."

Agreed, but the number one problem with our (PHP) community, is that every tom/dick/harry decides that rolling their own is preferable to banding together behind a community driven platform - I've had to tear through enough muck, from self-taught devs, that I may be forever jaded; in 10 years, we'll all be enslaved to the Django/Rails (ha, maybe Sinatra) of the world, which would be a shame.