[plt-scheme] Online Scheme Programming Environment

Hi!

I'm starting a dissertation study whose subject is online scheme 
programming environment. Such that; you can write scheme programs, run 
or store them on it, just like you do with you local DrScheme IDE.

More precisely, I'm thinking to implement an R6RS compliant, fully 
functional Scheme interpreter which has proper tail-recursion and 
first-class continuations, with Javascript.

I started with examining SISC (http://sisc-scheme.org/). It is R5RS 
compliant Scheme interpreter written in Java.

But I need some guidelines, since it is my first really big dissertation 
study.

So I have two questions:

1 - What would be the first thing comes to your mind about this, or your 
first expectation from this application?? (i.e. to have complete Planet 
libraries working on it)

2 - Do you have any suggestions, guidelines or daunts:) for your answer 
to 1??

Any ideas or advices are greatly welcome.

Regards,
Caner