Hi,
Just an observation - and there may be a good reason for this - but at the moment when you "Add" a file eg. a text file such as a .css or .js or whatever the system forces you to upload a text file first from your computer.
My suggestion would be to allow a user to "auto-generate blank file" or something which would allow them to just start typing straight into the asset, or cut and paste from an existing asset - (although I guess the clone tool would accomplish that)
I guess it would be helpful if you just wanted to bash out a little css or code fragment or something - or maybe i just missed a setting somewhere
Meanwhile this is my 2nd day exploring matrix and so far I'm very impressed - the only thing that mambo wins on is that it has it's own funny dance with a pole…
oh no hold on that's limbo 
Sorry about the double post - but I could just extend that idea a bit…
When you create a new design that file seems to hold all the information on that specific page but you can't seem to make individual parsable files that can then be associated to the root parsable design file - this would be particulary useful as matrix specific code chunks could then become assets in their own right and thus be reusable in other areas/sites rather than having to put all the matrix script on the one design file… it would be a bit "pseudOO" that way
Or mabye there is something I'm completely missing as I only just started with matrix…