Hi,
here two of my ideaa:
1. Website: The main website (e.g. www.sandbox-server.org ) contain general information, the information how to get an account/project, a link to a list of the projects/users and a "Thank you" for WMDE. The projects are under the project.<server name> and accessible per /~<project name> (userdir in Apache). The user pages (for own files and so on) are similar to the project page accessible per user.<server name>/~<user name>.
There should be a config interface, too. I think the address should be https://config.<server name>.
2. Software: The basic software should be Apache, PHP (maybe PHP 6.0 too for testing), MySQL and Perl. I think for security should PHP use fastcgi with suexec to run in Apache so the scripts are run as the owner. Fastcgi should give some performance.
What do you mean?
Best regards,
Jan