What do you mean by sandbox?
Assuming that you just want a general purpose storage solution, why not try out -dropbox
; or even,GmailAlthough Gmail clearly isn't intended for general file storage it provides 7gb and counting of free space ( per account ).
Alternatively, you could use github
for sharing code/text and soon we should have Google play
for all sorts of entertainment ( currently promising space for 20,000+ songs free of charge ).
There are actually hundreds if not thousands of options, it really depends on what you actually want to use it for.
You must bear in mind that the Mega' case set a precedent though..