Wrapper for WWW basically, BUT:
Provide Fire'n'Forget API with a callback function.
Provide local cache by System.IO if the platform supports.
Provide custom timeout to interrupt the loading process.
Include a Coroutiner class to start a coroutine or delay call from any script.
Derive from CustomYieldInstruction for custom coroutine in case.
Full source code and example included, and here's the web player example.
This has been tested only on Windows, made for my interactive project usage.
If you're interested in the cache feature on other platforms, please contact me.